CS12 and CS25 Cold Start Valve


These cold-start valves bleed air from the compressor head during the first few pump revolutions, reducing torque requirements for starting a motor. They are especially helpful on oil-lubed pumps that may be subject to low temperatures and low starting voltages, like contractor units that may sit outside overnight, connected to a long extension cord.

Install these valves into any convenient port upstream of the tank check valve, typically in a 1/8″ NPT port in the check valve, a port tapped in the head of the pump, or a tee in the discharge line. When the discharge line is at zero pressure, the CS valve is open, then when the pump starts, air flows out of the CS valve into the atmosphere. As the pump speed and discharge pressure increase, the valve snaps shut and stays closed until the end of the pump-up cycle. Upon unloading the head, the valve re-opens, ready for the next start-up.

  • Construction: Brass body and piston, fluorocarbon O-ring
  • Options: In-tank check valves available with CS12 installed
  • Pressure switch required for head unloading

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WARNING: This product can expose you to chemicals,

WARNING: This product can expose you to chemicals, including lead, which are known to the State of California to cause cancer and birth defects (or other reproductive harm). For more information go to www.p65Warnings.ca.gov


Symptoms of a faulty cold start valve:

  • Engine struggles to start – A faulty cold start injector may make it difficult to start your engine on a cold day. The car may take several attempted ignitions before the engine is finally able to turn over.
  • Engine stalling – After your engine starts, you may experience stalling while you drive. This will either occur at higher RPMs or when you take your foot off the pedal.
  • Rough idle – Your engine may produce loud noises or even vibrations when you are idling. This will happen as your car struggles to reach optimum running temperatures.

3. Engine performance issues

Engine performance issues are another symptom commonly associated with a bad or failing cold start injector. If a cold start injector fails or develops a large enough leak it can lead to engine performance issues. A leaky cold start injector may result in a reduction in engine performance and acceleration as a result of the disturbed air fuel ratio. In more severe cases, where a large amount of fuel is leaking into the manifold the vehicle may even experience stalling or misfires.

If your vehicle begins to display any of the symptoms above, or you suspect that your cold start injector has failed, have the vehicle diagnosed by a professional technician, such as one from YourMechanic, to determine if your car needs a cold start injector replacement.

Frequently Asked Questions

  1. How do I locate a local distributor for a special item?
  2. How do I obtain flow capacities for ASME safety valves?
  3. What is the difference between a safety valve and a relief valve?

1. How do I locate a local distributor for a special item?

Please contact us and we will put you in touch with a distributor in your area.

2. How do I obtain flow capacities for ASME safety valves?

The flow capacity charts for all of our safety valves are shown under the Products, ASME Safety Valve section of our web page.

3. What is the difference between a safety valve and a relief valve?

Control Devices offers two standard types of pressure relief devices for air.

A safety relief valve, or pop-off valve, is set to a predetermined pressure using a spring force to counteract the air pressure force. When the force created from the air pressure becomes greater than the spring force, the valve ‘pops’ fully open and vents air to the atmosphere. Safety relief valves are sized in such a manner that the valve will always have a greater flow capacity than the source creating the air pressure (i.e. an air compressor). The valve will remain open until a reseat pressure is reached. This reseat pressure varies with valve type and is usually between 35% to 75% of the set pressure. Control Devices has eight series of valves that are manufactured in accordance with Section VIII of the ASME Boiler and Pressure Vessel Code. We also manufacture a wide range of non-code valves. See our Products section for information on the valve types.

A relief valve is set to a predetermined pressure with a spring force counteracting the force created by the pressure from the air. When the force created from the pressure of the air becomes greater than the force of the spring, the valve will start to open and flow to atmosphere. As the pressure continues to increase, the valve will open further, allowing more flow. As the pressure decreases, the valve will close near the pressure at which it opened.

How can we help?

Our service team is available 7 days a week, Monday – Friday from 6 AM to 5 PM PST, Saturday – Sunday 7 AM – 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com