// Catalogue

On and Off 2/2 Way Valves for Air, Water, and Oil

2/2 way valves have two ports and two positions, so they do one job well: open a line or close it. TSA Hydraulics Engineering supplies them within the Directional Control family of our Valves range, for compressed air, water, oil and light process media.

Normally closed or normally open decides what happens when the power fails, and it is the easiest detail to get backwards. A tank that should stay sealed can drain, or a line that should vent can lock up. Tell us the fail safe state you need along with the model code. We will match a genuine valve or a well built equivalent.

7products

// Buying guide

How a 2/2 Way Valve Works

Inside the valve is a seal that either lifts off its seat or presses onto it. Most 2/2 valves use a poppet or diaphragm, which closes tightly with almost no leakage. Some hydraulic designs use a spool instead, which suits higher flows but allows a small internal leak.

The valve can be switched by a solenoid, by air pilot pressure or by hand. If the line must also vent when the valve closes, you need a 3/2 way valve instead.

Normally Closed or Normally Open?

Normally closed (NC): shut when the coil is off. This is the most common choice, used wherever flow should stop if power is lost.
Normally open (NO): open when the coil is off. This is used where flow must continue during a power cut, such as cooling water or a safety dump.

Check the symbol or the letters on the body, because NC and NO valves can look identical from the outside.

Direct Acting or Pilot Operated?

This detail catches out many buyers:

Direct acting: the coil lifts the seal on its own. It works from zero pressure, but only on small ports, because the coil must fight the full pressure.
Pilot operated: line pressure does most of the work. It handles bigger ports with a small coil, but needs a minimum pressure difference across the valve, often around 0.3 to 0.5 bar, to open properly.
Assisted lift: a mix of the two that opens from zero pressure on medium sizes.

If a pilot-operated valve will not open on a low pressure or gravity fed line, it is usually the wrong type, not a faulty valve.

Media and Seals

Match the seal and body to whatever flows through the valve:

NBR (nitrile): air, water and mineral oil.
EPDM: hot water, low pressure steam and some food duties, but not oil.
FKM: higher temperatures, fuels and many chemicals.
PTFE: aggressive chemicals and higher temperature steam.

Bodies come in brass for general use, stainless steel for food, water and corrosive duties, and steel or ductile iron for hydraulics.

Where 2/2 Way Valves Work

Switching compressed air, water and coolant on and off
Filling and draining tanks
Dumping hydraulic pressure or unloading an accumulator
Isolating a branch of a circuit for safety
Dosing and wash cycles in food, beverage and cleaning systems

Quick Troubleshooting

Will not open: check the coil voltage and, on pilot valves, the pressure difference.
Will not close fully: there may be dirt on the seat or a damaged diaphragm. Fit a strainer upstream.
AC coil humming loudly: often caused by dirt under the plunger or the wrong voltage.

2/2 Way Valves Specifications to Check

Port size and thread type
NC or NO
Direct acting, pilot operated or assisted lift, plus the minimum pressure difference
Maximum pressure and temperature
Seal and body material
Coil voltage, AC or DC, and the connector

Why Buy From TSA Hydraulics Engineering

As a 2/2 way valves supplier, we check NC or NO, the operating type and the minimum pressure, not just the port size. You get OEM or equivalent options, and help sourcing 2/2 way valves replacement parts such as coils, diaphragms and seal kits. We tell you upfront whether a valve is genuine or an equivalent.

// FAQs