Plastic Solenoid Valve

Plastic Solenoid Valves

Plastic solenoid valve media compatibility.

Plastic solenoid valves are available in Nylon, PVC, PVDF, POM (Delrin), PP and PTFE which are suited Plastic water appliance solenoid valvesfor a wide range of media depending on the valve type and materials of construction. Typically the low end cheap solenoid valves models such as nylon body water appliance valves used for domestic dishwashers, washing machines and general water dispensers with 3/4" BSP male water inlet and a choice of 10mm or 12mm single, double or triple hose barb outlets either at 90° degrees (downward) or 180°(straight). The picture on the right hand side shows this typical appliance valve range.

Plastic solenoid valves

There are a wide range of 2/2 way plastic solenoid valves that can be used for what we call a general purpose applications such as mains water systems, process water and irrigation systems, where this Plastic water solenoid valverange plastic valves are typically available 3/8", 1/2", 3/4", 1", 11/2 and 2" BSP thread (optional NPT thread). Typically available wih flow controller (turn screw of knob on the top) that offers users a means to control and reduce the water flow rate according to their requirements and a manual over ride facility so that these nylon water valves can be manually set into the open position without the need for electrical supply.

Plastic water solenoid valves

Users beware of cheap alternatives with solenoid coils that are not 100% duty rated i.e. not designed to withstand the coil heat build up when energised for more than two or three minutes. The same picture on the right hand side shows an irrigation solenoid valve with a 100% duty rated coil with electrical DIN connector, the cheaper models tend typically to have two thin wires or flying leads from the coil.

There is a wide range of plastic solenoid valves that can be used on slightly aggressive media, what we would term as middle of the range Nylon valve for RO watersuitable plastic valves that are better suited for caustic soda, pure water, de-mineralised water, RO (reverse osmosis) water and slightly aggressive and corrosive media such as slight acid and slight alkali media.

These valves typically with POM (Delrin) body and usually offer a choice of NBR, EPDM or FKM sealing with options without shading ring or with silver shading ring so there is no copper content within the solenoid valve.

The picture on the right hand side shows a nylon body 2/2 way zero rated (0 to 5 bar) plastic solenoid valve, port size about 1/2" thread probably BSP, however typically available BSP (G) Thread or NPT American thread, typical size range 1/2, 3/4 or 1". We have more information about threads here.

Nylon solenoid valves

There are also 2/2 way pressure assisted plastic Delrin solenoid valves available across a wider range of port sizes including 3/8, 1/2", Plastic material valves for pure water3/4",1", 11/4" and 11/2", pressure ranges typically 0.5 to 10 bar (must have at least 0.5 bar higher pressure on inlet port than outlet port).

Elastomer sealing options usually NBR, FKM and EPDM with some suppliers offering FFKM and silicone seal options.

Voltage options can be across the range including 12vDC, 24vDC, 48vDC and 24vAC, 110vAC and 230vAC 50/60Hz.

Plastic pilot solenoid valves

The top of the range plastic solenoid valve with a dry armature design (i.e. media only in contact with body and seal) can handle very aggressive and corrosive concentrated acid and alkali media. These can be supplied with Nylon, PVDF, PP, PTFE and PVC body. The choice of body material has to be selected according the the media passing through the valve in that the body material but not be affected and thus resist any corrosion or chemical attack from the media passing through the valve. PTFE is known to be resistant against most liquids but can be expensive in comparison to PVC and Nylon.

The second consideration is the solenoid seal, typically a PTFE solenoid valve will be available with a PTFE seal option, but PTFE is not flexible so sealing can be an issue and any even minute particles caught under the valve seat will prevent full closure, hence some solenoid valves have options for EPDM and FKM sealing.

PTFE solenoid valves

Plastic solenoid valve internal construction

Plastic solenoid valves will have various materials of construction from Nylon, POM (Delrin), PVC, PP, PVDF or PTFE, their internal parts typically being various grades of brass, plastic or stainless steel, i.e. 430F armature, AISI302 for springs, AISI304 for the core tube and any pressure support discs if used in conjunction with a sealing diaphragm. The exception to this rule are the dry armature or isolated diaphragm valves where the media passing through the valve is ONLY in contact with the valve body and the seal, such as typically found with PTFE solenoid valves that are specifically designed for concentrated acid or alkali media.

Plastic solenoid valve seals

Typically fitted with NBR seals as standard with options for EPDM, FKM, PTFE.

Plastic solenoid valve pressure and size ranges.

Miniature plastic solenoid valves typically 0 to 8 bar, Port sizes 1/8, 1/4,3/8 and 1/2" thread.

Zero rated plastic solenoid valves typically 0 to 10 Bar, Port sizes 3/8, 1/2, 3/4 or 1" thread.

Pilot operated plastic solenoid valves typically 0.2/0.5 up to 10 bar, Port sizes 3/8, 1/2, 3/4, 1, 11/4, 11/2 and 2" thread.

Benefits of Plastic Solenoid Valves

  • Benefits of Plastic Solenoid Valves
  • Good range of elastomer sealing.
  • Light weight
  • Typically the most cost effective solenoid valve.

Disadvantages of Plastic Solenoid Valves

  • Poor heat resistance.
  • Low pressure range.
  • Brittle weak valve body.
  • Limited range for larger sizes or flanged connections.