Frequently Asked Questions about Solenoid Valves

Here are a collection of popular questions about solenoid valves and if the answer you seek isn't here, please contact us directly and we'll be able to explain it for you.

Can a solenoid valve be mounted in any position?

Not all of them, no. Check the manufacturer instructions for the model you intend to use as some can only be mounted in a horizontal pipe with the coil vertical and upright.

The valve is making a lot of noise, is that normal?

All coils used on AC supplies will hum when energised but any vibrating or rattling should be investigated and rectified quickly. Solenoid coils should be firmly secured to their armature for efficiency and if not tight, could be the reason for any noise.

Why do solenoid coils get so hot?

The solenoid coil is an electromagnet and the heat generated is a byproduct of the magnetic field creation process. Most coils are designed for continuous operation and it is completely normal for them to be too hot to touch when in operation.

Is it possible for solenoid valves to heat the fluid going through them?

The operation of the solenoid valve cannot directly heat the fluid but since the coil does get hot, it will radiate and convect heat through the air to the surrounding area. In a confined space or when a valve is inverted with the coil beneath the pipework, convection currents will carry warmed air to the pipework and could heat the contents. Note that any cold fluid passing through the valve would have a cooling effect on the valve and pipework and any increases in temperature would likely be negligible. However it would always be recommended to house the solenoid valve where free air can circulate to prevent excessive heat build up which could shorten the working life of the coil.

Should I get a WRAS certified valve for use on drinking water?

Non-WRAS valves can have elastomers that could impart an unpleasant flavour to drinking water and we would always recommend WRAS valves for potable use even if not required by legislation.

Can I fit another manufacturer's coil on my solenoid valve?

The clearance tolerance between the coil mounting hole and the armature is critical for reliable operation and the matching coil winding will also be specifically designed for efficiency. Since there is no international standard for coil and armature construction, every manufacturer designs them to suit their requirements and in the main, they are not exchangeable at all. However, some coils do have similar internal diameters and heights and can be seen swapped onto the wrong valves on many plants. This rarely works well or for long and for reliability, it would always be best to maintain the valve by using the recommended coil from the same manufacturer.

Can I change my valve to DC operation from AC or vice versa just by changing the coil?

Not usually, no. Both the armature and coil designs are different for AC and DC voltages and doing this exchange is likely to produce reliability issues in addition to wasting energy. This can be done on some valve designs but always check with the manufacturer or distributor first.

Can I use solenoid valves on flow in either direction?

Most 2/2 solenoid valves can only be used with flow in a single direction. However, some designs are capable of working with bidirectional flow. Contact us to discuss your requirements if this is of interest.

Can I get a solenoid valve with ATEX certification for Zone 1 externally and Zone 0 internally?

No, The ATEX certification only covers the atmospheric risks where the valve is installed. It is not possible to certify a valve against risk of combustion of the fluid travelling through it.

Why can't I fit my coil back onto the solenoid valve after testing it?

Solenoid coils must never be energised without being secured to the valve armature. Doing this will cause excessive heat build up and the coil will fail, producing bulges within the mounting hole and /or externally. Loose coils will produce exactly the same result but over a longer period of time. If the coil used to fit and now doesn't, you need a new coil. If the coil cannot be removed because it has expanded onto the armature, you need a complete new valve.

What's the polarity of the coil so that I can wire it up?

Most solenoid coils are unpolarised so that it doesn't matter which of the two coil connections are positive/negative or live/neutral. If a coil is polarised, it will state it clearly in the installation instructions and would only apply to DC circuits. Commonly this would be for latching coils or ones with additional control circuitry.

How can I open/close the solenoid valve without powering it?

Some solenoid valves include a manual operator feature which is a push button or a screwdriver actuated twist head to manually lift the valve off the seat. Without a manual operator, the only other option is to remove the coil and fit a Commissioning Magnet in its place and remove it when finished. In this way, the magnetic field of the permanent magnet replaces the electromagnetic field created when the coil is energised.

Why will my normally closed solenoid valve not shut off?

There could be a number of reasons depending on the model involved. Perhaps the manual operator has been left in the open position if there is one fitted. If not, consider that when the valve opens, the distance the diaphragm or piston moves off the seat is only small and can become clogged with particulates or debris and prevent the valve shutting completely. Another reason could be damage to the diaphragm. These all assume that the valve was installed according to the manufacturer's instructions. Fitting a valve contrary to the marked flow direction will prevent the valve shutting. Some valves require a minimum pressure drop across the valve to ensure the diaphragm seats securely. With insufficient pressure, the diaphragm can float and the valve can open and close unpredictably. For this reason, pilot operated or servo type solenoid valves should not be used in closed loop or low pressure systems.

What fluids can't be used with solenoid valves?

There are highly specialised valves on the market for some difficult media such as glues and heavy fuel oil but in general, highly viscous media are not suitable. Equally fluids with a large particulate content would quickly prevent reliable operation. Foodstuffs like milk for example could be used in solenoid valves because they are not too viscous but would not be recommended as the valves are not suitable for CIP or SIP cleaning processes and cannot easily be inspected for manual cleaning to prevent bacterial contamination.

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+44 (0) 1443 772500 / 02922 780798

Red Dragon Limited T/A
Measure Monitor Control
Unit 15 Abergorki Industrial
Ynyswen Road
South Wales
CF42 6DL
United Kingdom
EORI: GB791056521000

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