Help & F.A.Q

What information would I need to properly size a pressure regulator for my application?
• Materials of construction requirements (media info. gas/liquid, specific gravity...)
• Inlet pressure (are there any supply pressure affect concerns?)
• Outlet pressure set point
• Flow coefficient (Cv) or flow requirements (LPM, SCFM, GPM, etc.)
• Minimum/Maximum operating temperatures (process and ambient)
• Type and size of connections that are required

What is a 'single stage pressure reducing regulator'?
A regulator which reduces high pressure to low pressure and controls the low (or outlet) pressure with one stage of pressure reduction.

What is a 'dual (or two stage) stage pressure reducing regulator'?
A regulator which reduces high pressure to low pressure and controls the low (or outlet) pressure with two stage of pressure reduction (used when more stability of operation is required).

What is a 'back pressure regulator'?
A regulator used for controlling and maintaining the inlet pressure (upstream pressure) rather than reducing it.

What is a 'heated pressure regulator?
A regulator used to supply heat to samples entering instrumentation systems. They can be used to pre-heat liquids, to prevent condensation of gases or to vapourise liquids prior to gas analysis.

What is inlet or supply pressure affect (often referred to as 'decaying inlet pressure')?
This is the change in set pressure that results from changes in inlet pressure to the pressure regulator. An example would be the change in set pressure that results as inlet pressure to a pressure regulator from a cylinder bottle drops as it empties.

Why does the outlet pressure from my pressure regulator continue to rise after flow is stopped through the regulator (i.e., a valve is closed downstream of the pressure regulator)?
This is most commonly referred to as "creep" or "seat leakage". The cause of "creep" or "seat leakage" is typically debris or contamination that has become lodged into the main valve assembly of the pressure regulator. This will not allow the main valve in the regulator to completely close, which allows inlet pressure to "creep" by the seat and causes outlet pressure to continue to rise. In some cases the seat and poppet can be removed, cleaned and reinstalled to solve this problem, but if the contamination damaged any of these parts, they would need to be replaced. The occurrence of Creep and seat leakage can be minimized by the installation of a filter in front of your pressure regulator.

What is 'Droop'?
This is the amount of outlet pressure decrease with respect to increasing flow demand on a pressure reducing regulator. It can be expressed in percentage change of the set-point or can be shown as pounds per square inch change with respect to flow increase.

What is 'Lock-Up'?
This is the amount of outlet pressure increase, beyond the set pressure, with respect to decreasing flow demand an a pressure reducing regulator.

What is a 'balanced poppet'?
This is a design description of the poppet assembly wherein the forces exerted on the top and bottom of the poppet are equal.

                         Click here for pdf.

The IP rating system provides a means of classifying the degrees of protection from dust, water and impact afforded by elctrical equipment and enclosures. The system is recognised in most European countries and is set out in a number of British and European standards. These include BS5490:1977 (IEC529:1976) Classification of Degrees of Protection Provided by Enclosures, BS5420:1977 (IEC144:1963) Specification for Degrees of Protection of Enclosures of Switchgear and Control Gear for Voltages up to and including 1000VAC and 1200 VDC.

Degrees of Protection - First Digit
The first digit of the IP code indicates the degree that the equipment is protected against solid foreign bodies intruding into an enclosure.

0 - No special protection
1 - Protection against solid objects over 50mm diameter e.g. accidental touch by both hands.
2 - Protection against solid objects over 12mm diameter e.g. fingers.
3 - Protection against solid objects over 2.5mm (tools and wires)
4 - Protection against solid objects over 1.0mm (tools, wires and small wires)
5 - Protection against dust - limited ingress (no harmful deposit)
6 - Totally protected against dust.

Degrees of Protection - Second Digit
The second digit indicates the degree that the equipment is protected against liquids and mositure.

0 - No special protection
1 - Protection from vertically falling drops of water.
2 - Protection from direct sprays of water up to 15° from the vertical.
3 - Protection from sprays up to 60° from the vertical.
4 - Protection from water sprayed from all directions - limited ingress permitted.
5 - Protection from low pressure jets of water from all directions - limited ingress permitted.
6 - Protection against strong jets of water e.g. for use on shipdecks - limited ingress permitted.
7 - Protection against the effects of immersion between 15cm and 1m.
8 - Protection against long periods of immersion under pressure.

Viscosity is the resistance of a fluid to flow. The classic definition is the ratio of shear stress to shear rate. Imagine two plates seperated by a distance x, of area A, with the space between filled with a liquid. If you push sideways on the top plate with a force F and as a result it moves at a speed V, then the viscosity of the liquid is:

viscosity = (F/A)/(V/x)

The unit of viscosity is centipoise (cp) or millipascal-seconds (same thing)

What you should know about pressure reducing valves
Pressure reducing valves reduce a high and frequently fluctuating pressure to an adjustable constant pressure downstream of the valve. A spring keeps the valve open and this closes as the outlet pressure rises.

Selecting valve type and nominal diameter
Using your maximum operating data and the smallest differential pressure ?p, you should calculate the characteristic performance figure Kv (see leaflet Calculation of Pressure Regulators). Select a valve whose Kvs value is 30% greater than the calculated Kv figure. Additional allowances must be made for high-viscosity liquids or liquids which vaporise when depressurised. You should also note the reduction ratio i.e. inlet pressure p1 divided by outlet pressure p2. The inlet pressure acting on the cone causes the valve to open whereas the outlet pressure acting on the diaphragm/spring system causes it to close. If the reduction ratio calculated from the operating data is greater than the quoted ratio, the valve will not close. Pressure reducing valves should not be overdimensioned. Their optimum working range is within 10% to 70% of their Kvs value.

Selecting rated pressure and valve material
The rated pressure must exceed the maximum system pressure, irrespective of safety allowances. Please note also the effect of the temperature (see DIN 2401).

Selecting the setting range
For good control accuracy you should select a setting range which places the required outlet pressure near its upper limit. If, for example, the controlled outlet pressure is to be 2.3 bar, you should select the 0.8 to 2.5 bar setting range, not 2 to 5 bar. If the available setting range is not wide enough you may go below the bottom limit of the setting range provided that the valve loading is kept low and a high control accuracy not required.

Selecting elastomer materials
You should select elastomers according to the operating temperature and the requirements of the medium. High-pressure gases, for example, can diffuse into the elastomer and cause damage when being depressurised.

Flow velocity
Depending on pressure drop and permitted maximum noise level, we recommend the following flow velocities:

liquids 1 - 5 m/s
saturated steam 10 - 40 m/s
superheated steam 15 - 60 m/s
gases up to 2 bar 2 - 10 m/s
gases above 2 bar 5 - 40 m/s

Sense line (control line)
You should install a sense line if the selected pressure reducer is designed for sense line operation. The sense line should be connected at a distance of not less than 10 times nominal diameter downstream of the pressure reducing valve. No isolating valves should be installed in the sense line to avoid an excessive pressure differential between valve body and diaphragm. To attenuate any oscillations occurring in the pipeline system, the sense line may be fitted with a restrictor which must never be fully closed during operation. In the case of steam and liquids the sense line must be installed so as to fall towards the valve. Under special operating conditions, for example intermittent operation with dry steam, an compensation vessel must be installed. The sense line must be rigid as elastic hoses can induce oscillations.

Protecting your system
To protect your system you should install a safety valve downstream of the pressure reducer to prevent the maximum permitted operating pressure (normally 1.5 x maximum set pressure) being exceeded. The safety valve operating pressure should be set approximately 40% above the maximum set pressure of the pressure reducer to avoid blow-off during slight pressure fluctuations.

For example: if the pressure reducer setting range is 2 - 5 bar the safety valve operating pressure must be 1.4 x 5 bar = 7 bar.

Protecting the pressure reducing valve
To protect the pressure reducer against damage from solid particles carried in the pipeline, a strainer or filter should be fitted and serviced at regular intervals.

With steam as medium, the pressure reducer should be preceded by a water trap, which is also called steam dryer, to protect it from cavitation (see below chapter "Steam Operation").

Valve seat leakage
Pressure reducers are control valves which are not required to provide a leak-proof seal (VDI/VDE Guideline 2174). Normally pressure reducers leave the factory with perfectly leakproof valve seats. During operation, however, solid particles often cause damage and seat leakage. Any low leakage requirement must be expressly specified when ordering. Valve leakage can be considerably reduced by special measures such as lapping the valve seat, using special cone seals and increasing the control (diaphragm) surfaces.

Cut-off
For the purpose of installation, servicing and isolation of the valve, shut-off valves should be installed upstream and downstream of the pressure reducer. When closing the shut-off valves the upstream valve must always be closed first. A bypass line may be necessary to maintain emergency operation.

Stellited seat and cone
In the case of abrasive media or liquids with pressure drops (inlet pressure minus outlet pressure) of more than 25 bar the valve cone must be stellited; for pressure drops above 150 bar the seat must be stellited as well

Leakage line
If toxic or hazardous media are used the valve must feature a sealed spring cap (including setting spindle seal) fitted with a leakage line connection. When the pressure reducer is installed on site a leakage line must be fitted capable of safely and pressureless draining the escaping medium in case the control valve should become defective.

Mounting position
For gases a pressure reducing valve can normally be fitted in horizontal pipelines with the spring cap at the bottom or at the top. Installation in vertical pipe runs is possible but can result in increased wear and loss of control accuracy owing to increased friction. In the case of liquids a pressure reducer should be installed with the spring cover at the bottom. Thus gas traps upstream of the valve are avoided which would cause the valve to oscillate. For steam a pressure reducer should likewise be installed with its spring cover at the bottom to protect the diaphragm against overheating by means of a layer of condensate.

Start-up
Pressure reducers should be started up and operated without pressure surges, if possible. A sudden operation of upstream or downstream valves should be avoided.

Steam operation
If a pressure reducer is installed in a steam plant the diaphragm water reservoir must be filled before the plant is started up. There must be no danger of overheating at the installation site caused by excessive ambient temperatures or insufficient heat dissipation. Pressure regulators must not be insolated. In some cases an insulating of the body is permitted, but only with cast bodies. Neve4r insulate diaphragm housing, mid section and spring cap (or open springs). Overhearing caused by insulating destroys the elastomere of the control unit.

Many steam generators send a lot of water through the piping together with the steam. Even an initial overheating can get lost through piping heat losses, so that the steam gets "wet". A piping speed of up to 25 m/s is normal for "dry steam", whilst wet steam already has the effect of a sandblasting machine at this speed, and the condensate and/or the water droplets eat holes into pipings and valve seats. In addition, water obstructs heat transition especially in heat exchangers. To avoid it, the water should be removed by a water trap, also called steam dryer, as quickly as possible and without steam losses.

Setting the pressure
Pressure reducing valves are normally supplied by us with a relaxed spring. This means that a valve is set at the factory to the minimum outlet pressure. The required pressure should be set under operating conditions.

Maintenance
Pressure reducers must be cleaned and serviced regularly.

Valves free of oil and grease or silicone.
Please pay attention to order an fit only spares free of oil and grease resp. free of silicone.

Guidelines for selection, installation and operation, "Notes on Safety, Operating Instruction etc." MUST be followed.

Please consult our engineer if extreme operating conditions apply or whenever you are in doubt.

What you should know about vacuum valves

What you should know about Overflow Valves
Overflow valves control an adjustable constant pressure upstream of the valve. A spring keeps the valve closed. As the inlet pressure rises the valve opens.

Selecting valve type and nominal diameter
Using your maximum operating data and the smallest differential pressure Dp, you should calculate the characteristic performance figure Kv (see leaflet Calculation of Pressure Regulators). Select a valve whose Kvs value is 30% greater than the calculated Kv figure. Additional allowances must be made for high-viscosity liquids or liquids which vaporise when depressurised. Overflow valves should not be overdimensioned. Their optimum working range is within 10% to 70% of their Kvs value.

Selecting rated pressure and valve material
The rated pressure must exceed the maximum system pressure, irrespective of safety allowances. Please note also the effect of the temperature (see DIN 2401).

Selecting the setting range
For good control accuracy you should select a setting range which places the required inlet pressure near its upper limit. If, for example, the controlled inlet pressure is to be 2.3 bar, you should select the 0.8 to 2.5 bar setting range, not 2 to 5 bar. If the available setting range is not wide enough you may go below the bottom limit of the setting range provided that the valve loading is kept low and a high control accuracy not required.

Selecting elastomer materials
You should select eleastomers according to the operating temperature and the requirements of the medium. High-pressure gases, for example, can diffuse into the elastomer and cause damage when being depressurised.

Flow velocity
Depending on pressure drop and permitted maximum noise level, we recommend the following flow velocities:

liquids 1 - 5 m/s
saturated steam 10 - 40 m/s
superheated steam 15 - 60 m/s
gases up to 2 bar 2 - 10 m/s
gases above 2 bar 5 - 40 m/s

Sense line (control line)
You should install a sense line if the selected overflow valve is designed for sense line operation. The sense line should be connected at a distance of not less than 10 times nominal diameter upstream of the pressure reducing valve. No isolating valves should be installed in the sense line to avoid an excessive pressure differential between valve body and diaphragm. To attenuate any oscillations occurring in the pipeline system, the sense line may be fitted with a restrictor which must never be fully closed during operation. In the case of steam and liquids the sense line must be installed so as to fall towards the valve. Under special operating conditions, for example intermittent operation with dry steam, an compensation vessel must be installed. The sense line must be rigid as elastic hoses can induce oscillations.

Protecting your system
To protect your system you should install a safety valve upstream of the overflow valve to prevent the maximum permitted operating pressure (normally 1.5 x maximum set pressure) being exceeded. The safety valve operating pressure should be set approximately 40% above the maximum set pressure of the overflow valve to avoid blow-off during slight pressure fluctuations. For example: if the overflow valve setting range is 2 - 5 bar the safety valve operating pressure must be 1.4 x 5 bar = 7 bar.

Protecting the overflow valve
To protect the overflow valve against damage from solid particles carried in the pipeline, a strainer or filter should be fitted and serviced at regular intervals.

With steam as medium, the pressure reducer should be preceded by a water trap, which is also called steam dryer, to protect it from cavitation (see below chapter "Steam Operation").

Valve seat leakage
overflow valves are control valves which are not required to provide a leak-proof seal (VDI/VDE Guideline 2174). Normally overflow valves leave the factory with perfectly leakproof valve seats. During operation, however, solid particles often cause damage and seat leakage. Any low leakage requirement must be expressly specified when ordering. Valve leakage can be considerably reduced by special measures such as lapping the valve seat, using special cone seals and increasing the control (diaphragm) surfaces.

Cut-off
For the purpose of installation, servicing and isolation of the valve, shut-off valves should be installed upstream and downstream of the overflow valve. When closing the shut-off valves the upstream valve must always be closed first. A bypass line may be necessary to maintain emergency operation.

Stellited seat and cone
In the case of abrasive media or liquids with pressure drops (inlet pressure minus outlet pressure) of more than 25 bar the valve cone must be stellited; for pressure drops above 150 bar the seat must be stellited as well.

Leakage line
If toxic or hazardous media are used the valve must feature a sealed spring cap (including setting spindle seal) fitted with a leakage line connection. When the overflow valve is installed on site a leakage line must be fitted capable of safely and pressureless draining the escaping medium in case the control valve should become defective.

Mounting position
For gases a pressure reducing valve can normally be fitted in horizontal pipelines with the spring cap at the bottom or at the top. Installation in vertical pipe runs is possible but can result in increased wear and loss of control accuracy owing to increased friction. In the case of liquids a overflow valve should be installed with the spring cover at the bottom. Thus gas traps upstream of the valve are avoided which would cause the valve to oscillate. For steam a overflow valve should likewise be installed with its spring cover at the bottom to protect the diaphragm against overheating by means of a layer of condensate.

Start-up
overflow valves should be started up and operated without pressure surges, if possible. A sudden operation of upstream or downstream valves should be avoided.

Steam operation
If a overflow valve is installed in a steam plant the diaphragm water reservoir must be filled before the plant is started up. There must be no danger of overheating at the installation site caused by excessive ambient temperatures or insufficient heat dissipation. Overflow valve must not be insolated. In some cases an insulating of the body is permitted, but only with cast bodies. Neve4r insulate diaphragm housing, mid section and spring cap (or open springs). Overhearing caused by insulating destroys the elastomere of the control unit.

Many steam generators send a lot of water through the piping together with the steam. Even an initial overheating can get lost through piping heat losses, so that the steam gets "wet". A piping speed of up to 25 m/s is normal for "dry steam", whilst wet steam already has the effect of a sandblasting machine at this speed, and the condensate and/or the water droplets eat holes into pipings and valve seats. In addition, water obstructs heat transition especially in heat exchangers. To avoid it, the water should be removed by a water trap, also called steam dryer, as quickly as possible and without steam losses.

Setting the pressure
Pressure reducing valves are normally supplied by us with a relaxed spring. This means that a valve is set at the factory to the minimuminlet pressure. The required pressure should be set under operating conditions.

Maintenance
Overflow valves must be cleaned and serviced regularly.

Valves free of oil and grease or silicone.
Please pay attention to order an fit only spares free of oil and grease resp. free of silicone.

Guidelines for selection, installation and operation, "Notes on Safety, Operating Instruction etc. MUST be followed.

Please consult our engineer if extreme operating conditions apply or whenever you are in doubt.

What you should know about safety valves
Safety valves are the ultimate protection device for tanks and pipelines. They prevent pressure limits being exceeded once all automatic control and monitoring equipment has failed.

Normal safety valves initially open proportionally up to a pressure rise of 10%. This initial phase is followed by the full opening of the valve, allowing a large flow of medium. Especially in the case of liquids, the wide proportional range results in a continuous operation.

Pressure rise:
above 1 bar set pressure: 10% up to required valve lift;
below 1 bar set pressure: 0.1 bar.

Proportional safety valves open almost continuously as the pressure rises. They produce the valve lift required for draining the volume within a maximum pressure rise of 10%. They are used where only small volumes are expected to be drained (e.g. thermal expansion) and where the loss of medium is to be minimised.

Pressure rise:
above 1 bar set pressure: 10% up to required valve lift;
below 1 bar set pressure: 0.1 bar.

Full lift safety valves open instantly up to maximum lift within a pressure rise of 5%. Because of their instant opening they are used where suddenly larger flow volumes or fast pressure rises may occur. They are mainly used for relieving pressure in vapours and gases.

Pressure rise:
above 1 bar set pressure: 5% up to the max. valve lift;
below 1 bar set pressure: 0.1 bar.

Closing pressure difference
compressible media: 10%
below 3 bar: 0,3 bar
non-compressible media: 20%
below 3 bar: 0,6 bar

System operating pressure
The plant or system operating pressure should be at least 5% below the safety valve closing pressure to ensure that the safety valve closes correctly.

Variable back pressure
During blow-off the variable back pressure created by blowing-off must not exceed 15% of the valve operating pressure. If the variable back pressure is more than 15% of the valve operating pressure, the valve capacity must be checked. For higher pressures safety valves fitted with pressure-compensating metal bellows should be used.

External back pressure
A constant external back pressure (caused by the system) can be compensated by selecting a suitable spring. In this case the above statements are not applicable.

Installation
Safety valves must always be installed with the spring cover at the top.

Safety valve inlet
The inlet spigots for safety valves should be as short as possible and must not produce a pressure drop exceeding 3% of the valve operating pressure. If the pressure drop is greater, the inlet pipeline diameter should be increased. The edge of the inlet spigot should be chamfered or rounded.

Blow-off pipeline
For vapours or gases the blow-off pipeline should rise, whilst for liquids it should be installed with a fall. Please make sure that a blowing safety valve does not create a hazard, especially when a safety valve with open spring cover is installed.

Draining of condensate
To keep away dirt and foreign bodies from the safety valve, the blow-off line must have a condensate drain installed at its lowest point. In addition a drain orifice may be provided in the valve itself (this may be necessary for special operating environments such as ships). Before commissioning the valve the plastic plug inserted by the manufacturer must be replaced by a screwed plug.

Drain lines must have no constriction; they must have a fall away from the valve and an outlet which is open to view; the draining of the medium must not create a hazard. If the medium is steam the above requirement can be met by installing steam traps.

Leakage
Safety valves fitted with bellows feature a relief orifice in the spring cover. If medium leaks from this orifice, the bellows is faulty. In the case of toxic or hazardous media you must make sure that these are drained safely.

Insulation
If insulation is used it must not be applied to the spring cover or cooling area (if provided).

Maintenance
Safety valves must be cleaned and serviced at regular intervals. The service intervals depend on the ambient atmosphere(corrosive, dirty) and mode of operation(occasional, continual).

Function check
From time to time the valve should be checked for correct functioning either by manual venting or blowing off. Steam generators are subject to the regulations given in Section 6 of TRD 601 Sheet 1, Issue 6.83.

A slight leakage can be cured by blowing-off. If this does not stop the leak the sealing surfaces are probably damaged. The valve should be closed by a sudden release of the venting lever. After testing the lever must no longer be engaged with the coupling. To disengage the lever it should be pushed towards the centre of the spring cover until the venting fork is free.

Valves free of oil and grease or silicone.
Please pay attention to order an fit only spares free of oil and grease resp. free of silicone.

Guidelines for selection, installation and operation, "Notes on Safety, Operating Instruction etc." MUST be followed.

Please consult our engineer if extreme operating conditions apply or whenever you are in doubt.

What you should know about Bleed and Venting Valves
Bleed and venting valves remove or admit air or gases automatically from/to tanks, vessels or pipelines. They are float-controlled valves which close as the liquid level rises and open as the level falls.

Operation
A rising liquid level lifts the float and closes the valve, in most cases via a system of levers. If the liquid level drops because air is entering the system or the plant is being started up, the valve will open and either admit air or vent the air from the system.

Start-up vent valves are used to vent low-pressure plant systems when such systems are started up or filled. The float acts directly on the cone. They have a large seat diameter to ensure fast venting for pressures below 0.1 bar. During operation these valves are kept closed by the internal system pressure. A suddenly occurring vacuum causes them to open and equalise the pressure. This prevents damage which a vacuum may cause.

Continuous vent valves are used to remove air which accumulates as the plant operates. They incorporate a lever system which enables them to operate at very low and high pressures. A non-return valve can be fitted to the outlet side of these valves to prevent air entering the system. In this case they are pure vent valves, no air enters the system.

Double function vent valves are combined start-up and continuous bleed/venting valves. They have a large seat for start-up operation and a small seat for continuous operation, which are controlled by a float via a system of levers. Both valve seats are open while the system is being filled. During system operation the large seat is kept closed by the internal pressure. Any accumulating small air volumes are vented from the system via the small valve seat. If the pressure drops below 0.1 bar the large valve seat can open again. If a vacuum occurs which may be caused, for instance, by a pump failure, the large seat opens instantaneously and prevents damage. If subsequently a pressure surge runs back through the pipeline, the large seat closes causing the air volume which has entered the system to act as a damper while escaping to atmosphere through the small seat.

Elastomers and coatings
Standard valves can be used for water up to 80 °C, in certain cases up to 130 °C, higher temperatures with special types. For ozone we supply a special version fitted with special elastomers. For hydrocarbons like petrol, gasoline etc. we use FPM. For hot mineral water, sea water and other liquids containing chloride we supply valves that feature coated bodies and internal components. For corrosive media we supply rubber-coated valves. In addition we can supply special valves manufactured from high-molybdenum materials. Please note that our stainless steel venting valves are in most cases cheaper than equivalent cast iron valves.

Operating pressure range
You should select an operating pressure range which covers the maximum pressure that may occur, as otherwise the vent valve will not open. You should select the type and size of vent valve according to the air volume to be removed at operating pressure. You will find the appropriate tables in the data sheets. The throughput capacities given in these tables apply to a fully open valve i.e. when the system is started up or as long as the liquid level remains below the vent valve inlet. For steady and continuous venting, e.g. of filter vessels, the throughput capacity should be reduced by approximately 30%. To ensure smooth operation and long life, continuous vent valves should not be overdimensioned. If the throughput capacity is excessive for a given nominal diameter, a higher operating pressure coupled with a correspondingly lower throughput may provide the solution.

Installation
Vent valves should always be installed at high points in pipelines or vessels. Do not install vent valves on standpipes or in flushing lines but at those points where air accumulates. Select a pipe run where the flow velocity is reduced and, if required, install a vent dome. You should choose an installation site where the vent valve is not likely to "hammer" and thereby get damaged. During venting slugs of water must not be carried over and enter the valve body at high speed. If you are in doubt you should install a baffle or deflector. Please make sure that the cross-sectional area of the tank outlet is not less than that of the vent valve inlet. Under certain conditions (steam, foaming, very high flow velocity, contamination) a vent valve may "spit" i.e. discharge a small quantity of water when closing. For this reason it is recommended to fit a blow-off line to the outlet of the valve, if required. In the case of large air capacities, great turbulence, two-phase mixed media or side-mounting of the valve because of restricted headroom above the tank, a pipeline should be installed between the bleed valve cover and the highest point of the tank (i.e. a balancing line such as is used with level control valves). For this purpose the bleed valve cover must be fitted with an additional connector.

Pollution
If you have polluted liquids and the vent valve must be cleaned from time to time, please, install a stop valve between tank, vessel resp. pipeline and vent valve. This is not necessary if the equipment to be vented can be simple depressurized.

Pressure surges
Pressure surges or water hammer can destroy the float. You should take suitable measures to protect your plant.

Maintenance
Pressure reducers must be cleaned and serviced regularly, especially in the case of liquids containing compounds which tend to form deposits such as iron or lime.

Please consult our engineer if extreme operating conditions apply or whenever you are in doubt.

Guidelines for selection, installation and operation, "Notes on Safety", Operating Instruction MUST be followed.

What you should know about Float Valves
Level controllers and float valves control the liquid level in a vessel.

Level controller or float valve
You should use a level controller with float chamber if the float cannot be mounted in the vessel. It is mounted in the pipeline and connected to the vessel by means of balancing lines. Float valves have no float chamber. The float is always mounted in the vessel.

Feed and drain valves
Feed valves (code letter "Z") close as the float rises and prevent overflowing. Drain valves (code letter "A") close as the float sinks and ensure that the liquid level does not drop below the required level.

Mounting of float-controlled valves
Float valves for installations in vessels are mounted inside the vessel complete with float. Float valves for installation on vessels are flangemounted on the outer skin of the vessel. Float valves for installation in pipe lines are installed in the feed/drain pipe. The float lever either projects into the vessel or the float movemen´s is transferred by means of a cable.

Flow direction of float valves
The flow direction determines the mounting arrangement and type of float lever used:
horizontal, flow direction towards or away from the vessel code letter "w"
vertical, flow direction upwards code letter "o"
vertical, flow direction downwards (code letter "u")

Selecting valve type and nominal diameter
To select the valve type and determine the required nominal diameter you should calculate first the operating performance parameter Kv based on the maximum operating values and minimum pressure drop Dp. You should choose a valve having a Kvs value which is 30% greater than the calculated Kv figure.

Selecting the operating pressure range
The maximum operating pressure of your system must be within the operating pressure range of the valve; if not, the float valve will not close or open.

Pressure inside the vessel
Check whether the vessel in which the float is to be mounted is not pressurised. If the vessel is pressurised a pressure-resistant ball float has to be fitted. Cylindrical floats may only be used in non-pressurised vessels.

Temperature
If the valve is to be used for temperatures above 80°C or a liquid other than water, the compatibility of the elastomers must be checked. For hydrocarbons like gasoline, petrol etc., for example, the valves are fitted with FPM elastomers, whilst for higher temperatures they are fitted with EPDM or, if necessary, with a metallic cone seal.

Adapting the float
Float valves are normally designed for media with the specific gravity of water. By choosing a different float geometry, by filling the float or by altering the operating pressure range, we can adapt the floats to other media.

Balance and double seat
Single seat non-balanced float valves are used for low pressures. They are relatively insensitive to contamination and dirt deposits.
Single seat balanced valves can be used for larger pressure drops and feature smaller floats.
Double seat valves are specially suitable for large flow rates.

Overflow preventers
A special product are the PTB-approved overflow preventers Types 36S and 36SF. These are mechanical safety devices for flammable liquids.

Seat leakage
Level controllers and float valves are control valves which are not required to provide a leak-proof seal(VDI/VDE Guideline 2174). For leakproof shutoff, shut-off valves must be used. Normally our valves leave the factory with perfectly leakproof valve seats. During operation, however, solid particles (e.g. sand, welding nuggets etc.) often cause damage and seat leakage. Any low leakage requirement must be expressly specified when ordering. Valve leakage can be considerably reduced by special measures such as lapping the valve seat, using special cone seals and increasing the valve closing force by changing the lever geometry or increasing the size of the float.

Adjustable filling level
In the case of valves fitted with float rod and adjustable float, the level in the vessel can be adjusted by sliding the float alon g the rod.

Float rod guide
For float rods a guide must be provided in the vessel to prevent the float oscillating. Float valves with parallel guide or special designs featuring a top-mounted float do not require a rod guide.

Operation
Make sure that no pressure surges or water hammer occur in the system, which could destroy the float. In the case of foaming media and the resulting reduction of the specific gravity, a float valve cannot operate reliably. In this case a foam abatement circuit should be provided.

Maintenance
Float valves and level controllers should be cleaned and serviced at regular intervals. This rule applies especially to valves which are rarely operated e.g. valves fitted in sprinkler systems. Thorough cleaning is important in the case of liquids containing substances which easily form deposits (such as iron, lime, suspended solids etc). Sand and abrasive particles carried along in the liquid can cause rapid wear. Please ask for specially adapted valves.

Valves free of oil and grease or silicone.
Please pay attention to order and fit only spares free of oil and grease resp. free of silicone.

Guidelines for selection, installation and operation, "Notes on Safety", Operating Instruction MUST be followed

Please consult our engineer if extreme operating conditions apply or whenever you are in doubt.

What you should know about Sightglasses/Flow Indicators
Sight glasses, flow indicators and flow meters indicate media and flow conditions in pipeline systems and plant

Selection
Sight glasses are monitoring equipment without indicating mechanisms.
Flow indicators have internal components that are set in motion by the flow.
Flow meters are fitted with a calibrated measuring scale and indicating flag.

Glasses
Sight glasses and flow indicators are supplied with one or two glasses. Two glasses enable the user to see through the medium. If the installation site is dark or if it is difficult to see the glass, a light may be fixed at the back which allows a better view of the flowing medium.

Glass qualities
Soda lime glass is used for temperatures up to 150°C (see DIN 8902); in the case of alkaline media (boiler water) only up to 100°C.
Maxos glass is used for temperatures up to 280°C (see DIN 7080).

Flow direction
Our standard flow indicators are supplied for left-to-right flow; we also supply indicators for right-to-left flow at the customer´s request. Please state the required flow direction when ordering.

Operating limit
Flow indicators and flow meters have an operating limit. Below this limit the flow is insufficient to set the internal components in motion (see Data Sheet).

Indicator flag for one direction
Flow indicators with flag and reset spring for one flow direction are the most popular type and can be installed in any position. Soda lime glasses feature a graduated scale of lines from 1 to 10. This scale allows the flow volume to be gauged easily and quickly. In many simple applications this type of indicator may be used as an alternative to an expensive flow meter. For the smaller DN (up to 1” / 25 mm) the indicating flag is supplied without a spring to allow it to indicate even small volumes. Vertical installation with flow from top to bottom, however, requires a spring.

Indicator flag for both directions
The centrally mounted flag is deflected towards the flow direction, thus indicating the direction of the flow. The position of the flag changes as the flow increases or decreases.

External indicator
For turbid or opaque liquids without magnetic contamination you should select a flow indicator with external pointer (Type 6.12). What has been said above under item “Indicator flag for one direction” applies to this type of indicator as well.

Ball-type indicator
The flow moves a ball from its rest position (at the bottom of the housing) to the top. This type of flow indicator must be installed vertically for flow from bottom to top.

Indicator with impeller
The flow causes the impeller to rotate. The speed of the impeller allows the flow volume to be gauged. Suitable for all installation positions as well as all pipeline flow speeds below 1 m/sec.

Wiper
Some media tend to deposit dirt on the internal surface of the glass. For such cases we supply a type fitted with an elastomer wiper. The wiper can be supplied only for single-glass flow indicators.

Flow meters
An internal weighted flag indicates the flow volume in m3/h water at 20°C on a calibrated scale. Flow meters can be supplied in two measuring ranges for each nominal diameter.

Resistance to media
The standard cover seal is not resistant to all media.

Installation
Please note the flow direction if you want to install a flow indicator with fixed direction of flow.

Operation
Flow indicators and sight glasses are quite simple units which do not require any special maintenance during operation. Dirty glasses should be cleaned and the cover seals renewed at the same time.

Maintenance
Remove the glass for cleaning. For reassembling the screws should be tightened evenly and diagonally using the specified torque, or the clamp ring seal tightened gently to avoid damaging the glass. We recommend that you keep a supply of replacement glasses.

Valves free of oil and grease or silicone.
Please pay attention to order and fit only spares free of oil and grease resp. free of silicone.

Guidelines for selection, installation and operation, "Notes on Safety", Operating Instruction MUST be followed

Please consult our engineer if extreme operating conditions apply or whenever you are in doubt.

What you should know about Filters/Strainers
Strainers and filters protect plant, plant components and equipment against damage and malfunctioning caused by contamination.

In what cases should a strainer be installed
After a pipeline system or plant has been commissioned, equipment or valves have been installed or repaired or pipes have been installed or welded, it may well be that dirt, welding nuggets, bits of sealing materials etc. have entered the system. Even during operation particles lodged in the pipes or fittings can become detached. These can cause malfunctioning by blocking small orifices or by forming deposits in control valves etc. For this reason we recommend that you should install strainers, gas filters or filters upstream of any equipment, control valves or fittings which may be at risk.

Even clean media such as sterile steam require suitable filter.

To protect our own pressure and flow control valves we always recommend fitting an upstream strainer or filter. This applies especially to regulating valves with small seat diameters i.e. small Kvs values. Mankenberg fit such protection devices to the pilot valves of pilot-controlled valves as standard equipment.

Selection
The type of strainer to be selected depends on the medium and temperature.

* Liquids - Strainers featuring one or more layers of mesh are particularly well suited for liquids. The mesh size depends on the downstream equipment. The smaller the control or measuring orifices, the finer must be the mesh size.

* Gases - For gases we use gas filters featuring non-woven filter fabric or, if a high degree of purity is required, a cartridge-type filter. As with strainers, the retained particle size of the filter is governed by the requirements of the downstream equipment.

* Steam - Our filter 6.06 is especially suitable for sterile and clean steam. Filter cartridges offering various retained particle sizes may be fitted.

Limits of application
Owing to the use of a synthetic fibre filter medium, the maximum temperature for gas filters is limited to 80°C. Filter 6.06 is designed for temperatures up to 190°C. Strainers must be used for all media exceeding this temperature.

Selecting valve type and nominal size
You must first ask which pressure drop is acceptable. If this is not all that important you should select the simplest equipment. In the case of strainers this is type 1.22 in Y-form. If the pressure drop is important you should select the potl type. With this type the mesh area which is relatively large compared with the nominal diameter, produces a considerably smaller pressure drop than a Y-type strainer with its small circular strainer mesh.

By using the Design Data sheet you can calculate the flow resistance. The flow resistance is a function of the retained particle size of the mesh or filter cartridge and of the mesh area. With strainers the larger nominal diameters feature larger mesh areas i.e. smaller pressure drops. If the calculated pressure loss should prove to be excessive you should check whether a larger mesh size can be used; if not, select a larger nominal diameter.

Valves free of oil and grease or silicone.
Please pay attention to order an fit only spares free of oil and grease resp. free of silicone.

Guidelines for selection, installation and operation, "Notes on Safety", Operating Instruction MUST be followed

Please consult our engineer if extreme operating conditions apply or whenever you are in doubt.

Q: Can I run my liquid sensor with gas?
A: Do not flow any gas through a liquid Flo-Sensor or Flo-Meter. This may damage the microturbine assembly and void the warranty.

Q: Does it matter what position I mount my sensor in?
A: McMillan Flo-Sensors and Flo-Meters have no particular installation requirements, so they may be mounted in any convenient position. For optimum results, however, the unit should be mounted with the mounting feet horizontal on top of a flat horizontal surface. This is the position the unit is calibrated in at the factory.

Q: May I install my own fittings?
A: Only use the factory installed fittings on the unit. If the fittings are removed, the calibration of the unit may be effected and leaking can occur. If different fittings are required, please contact Boiswood Customer Service for assistance.

Q: I bought a high-flow gas unit (2.0-10.0 L/M, range 9, and above) and want to remove the shunt/mounting plate. Will this affect the unit?
A: Yes. Do not disassemble the shunt/mounting plate or the unit will not operate correctly and the warranty will be void.

Q: I opened the unit and noticed that the wheel was wobbly and hitting the side. Is this a problem?
A: Do not disassemble your Flo-Meter or Flo-Sensor for any reason. If the unit appears to be malfunctioning, contact Boiswood Customer Services.

                     Material Compatability/Physical Properties of Gases

What is ATEX?
The ATEX Directive 94/9/EC is a Directive adopted by the European Union (EU) to facilitate free trade in the EU by aligning the technical and legal requirements in the Member States for products intended for use in potentially explosive atmospheres.

The ATEX Directive came into effect on a voluntary basis in 1996. Following this transition period the Directive was mandatory from 1st July 2003, applying to all products to be sold or used within the marketplace.

What does ATEX cover?
The ATEX Directive applies to both electrical and mechanical equipment and protective systems intended for use in potentially explosive atmospheres below ground, on the surface or on fixed offshore installations.

Potentially explosive atmospheres can exist in unlimited locations such as oil & gas platforms, factories, distilleries and chemical plants. Within these areas there are a number of potential ignition sources covered by the ATEX Directive. The three key indicators defining these are:

- Equipment and protective systems for use within potentially explosive atmospheres

- Devices used outside potentially explosive atmospheres but which assist in the safe operation of equipment and protective systems located within such atmospheres

- Components relating to the above.


Download a full copy of the ATEX 94/9/EC directive

                            Click here for further information.