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Race spec Safety Pressure Relief Valve with blowdown tube connection

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Wizards of NOS Nitrous Race Spec Safety Pressure Relief Valve

Race spec Safety Pressure Relief Valve with blowdown tube connection

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Wizards of NOS Nitrous Oxide Race Spec Safety Pressure Relief Valve

 This is the ultimate safety device and is unique to WON systems.

  • Adjustable to suit your desired working and/or safe nitrous pressure.
  • Highly accurate within approximately 50 psi of desired target pressure.
  • 6AN attachment suited for blow down hose and bulkhead fittings.
  • CNC machined, strong Stainless Steel body.
  • Ultra long life seals.
  • Compact aesthetic design.
  • 500 – 1500 psi adjustable working range
  • 1/4 BSP threads to suit a wide range of nitrous valves.
  • Lifetime guarantee.

Wizards of NOS developed the unique nitrous Safe Pressure Relief Valve (SPRV) to provide our customers with an increased level of safety that’s not available from any other nitrous company. The SPRV also boasts improved performance and reliability to compliment the other advanced, high quality market leading nitrous components WON offer.

The SPRV is a direct replacement for the basic and potentially dangerous blow off/rupture discs supplied as standard on all other brands of nitrous oxide bottle valve. It is designed to release small amounts of nitrous should the pressure in the bottle try to exceed the desired safe level, rather than dump the whole contents at an elevated unsafe pressure, as is the case with a blow off/rupture disc.

This Race Spec version allows for the use of a blow down tube or use of 6AN hose coupled with bulkhead fittings. The blow down is used to vent any over pressure to atmosphere outside of the vehicle. These valves are designed not to release the full contents of a cylinder like blow-off discs in their explosive manner. The SPRV will bleed progressively as pressure rises above the threshold in a safe and un-alarming manner and therefore do not require this tubing for safe function. However due to numerous regulations being unchanged to accomodate this technology we have provided this version where regulation needs it.


What is a blow off/rupture disc?

A blow off/rupture disc is a small disk usually made of brass or copper, which is retained in the back of the bottle valve as a weak link, much like a fuse is a weak link in an electrical circuit. If the pressure in the bottle reaches a certain level (usually ‘intended’ to be around 100 bar) the disc will rupture allowing all the bottle contents to escape. The idea is that the disc ruptures before the pressure becomes great enough to rupture the bottle itself.

There are however, numerous problems with such an arrangement;

1)      If you are close to the valve when the disc ruptures, it can result in a painful freeze burn because large volumes of liquid nitrous are rapidly dumped to atmosphere, in an a totally uncontrolled manner. To see a video demonstration of the results of this please  CLICK HERE

2)      You lose ALL the contents of your bottle.

3)      You have to buy and fit a replacement blow off disc before the bottle can be used again

4)      You then have to buy more gas (which can cost in excess of £80 + in some cases)

5)      You are then still at risk of a repeat of the failure.

Why you should switch to an SPRV?

An SPRV is a far better alternative to blow off/rupture discs for the following reasons;

1)      Rather than allowing the bottle pressure to exceed the safe working pressure by a substantial amount before dramatically rupturing, the SPRV opens IMMEDIATELY the safe pressure is exceed by even a small amount.

2)      When the safe pressure is exceeded instead of dumping the whole bottle contents, the SPRV just allows the EXCESS pressure to escape in a gaseous form in a slow and controlled manner, so there is no risk of a freeze burn.

3)      Once the pressure has returned to the desired normal level the SPRV will close, which prevents the loss of an entire bottle of gas and the inconvenience of having to replace a disc.

4)      Rather than being at risk of a repeat failure, you have the ongoing protection the SPRV offers, because it resets automatically.



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