XSS Valve, 300 Bar DIN outlet, 7/8 UNF inlet threads

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$69.00
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SKU
XSS-VX378-43A-VI
The XS 300 BAR DIN valve with 7/8 UNF neck thread is for Air Service Only. This unique valve is designed for use with smaller neck diameter High Pressure cylinders. The valve is rated for 4350 PSI service pressure.
This valve will NOT fit most modern scuba tanks, it is a replacement 300-bar valve intended for Luxfer composite aluminum and fiberglass wrapped cylinders that will also fit older steel cylinders with the smaller 7/8 UNF opening. This valve is NOT available in a Nitrox Ready version.

XSS Valve, 300 Bar DIN outlet, 7/8 UNF inlet threads

XSS Valve, 300 Bar DIN outlet, 7/8 UNF inlet threads
XSS Valve, 300 Bar DIN outlet, 7/8 UNF inlet threads
  • Unique valve size and design with 7/8"-14 UNF thread size
  • Dedicated {300 BAR |4,350 psi) DIN Outlet
  • Marine Grade Brass w/Triple Bright Chrome Plating
  • Includes the Vindicator handwheel knob
  • Air Service Only

The XSS 300 Bar DIN valve with the 7/8 UNF neck thread and XS Safety knob is made of marine grade brass with triple chrome plating for long life protection in salt water. Easy grip soft rubber safety hand wheel with stainless steel insert ensures long life and large ribs make turning handle easy even when wearing gloves. Valve has a dedicated DIN outlet for air service only at { 4350 psi | 300 bar } service pressure.

This 300 bar DIN valve can not be used with yoke regulators. A yoke adapter insert does not exist, and even if it were made, we have never seen a yoke clamp long enough to fit over a 300 bar DIN outlet. There is a yoke-to-din fill adapter device for 300 bar valves, but it is strictly for filling only.

This 300 bar DIN valve will fit older design 3500 psi "Genesis" steel SCUBA cylinders that are forced to use a 300 bar outlet because a valve with a 200 bar outlet AND the proper 7/8 UNF inlet threads to fit the cylinder is not available. If you wish, this valve could also be reduced { 3500 psi |240 bar} service pressure with a burst disk change.

This 300 bar DIN valve is marked as suitable for AIR ONLY service and is not available in an oxygen service version. The issue is not the cleanliness or material compatibility of the valve; rather the AIR ONLY restriction is as a result of the design, rated pressure and intended application of the valve itself. XS Scuba, the manufacturer, has communicated to Dive Gear Express that the valve should NOT be aftermarket prepared or modified in a misguided attempt to make it suitable for oxygen service.

More Information
SKU XSS-VX378-43A-VI
Brand XS Scuba
Weight (lbs) 1.5000
Customer Reviews
Most Helpful Customer Reviews
  1. 300 BAR DIN 7/8 UNF

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    Outstanding valve for my old steel 80 tank spun in Japan. As usual the service from DGX was impeccable.
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  2. Works

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    on

    The vale doze a good job for what I need
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SCUBA Cylinder Neck Threads in North America

When the now defunct Pressed Steel Tank Company (PST) manufactured a high-density steel 3500 psi service pressure SCUBA cylinder from the late 1980's until the early 2000's, they used a thread form for the neck opening known as Unified National Standard Fine. These cylinders were often sold under the brand "Sherwood Genesis" cylinders, and a similar version was occasionally imported from Japan under the name "Asahi". The specific thread form used with the steel 3500 psi SCUBA cylinder is named 0.875-14 UNF, often referred to as 7/8 UNF.

Today, the most common thread form used with SCUBA cylinders and valves is National Pipe Straight also known as NPS. The specific thread form used with most SCUBA cylinders is named 0.750-14 NPSM, often referred to as 3/4 NPS. This thread form is widely seen on both steel and aluminum SCUBA cylinders with service pressures of 2400+ (2640), 3000, 3180+ (3498), 3300 and 3442 psi. The current United States Department of Transportation rules prohibit the transport of metal scuba cylinders on public roads with pressures above 3442 psi (230 bar), even if the cylinders and gas delivery systems have been rated for higher pressures.

It's very important to understand that the 3/4 NPS and 7/8 UNF trade descriptions do NOT indicate relative sizes of the physical dimensions of the opening! This is because the two thread forms are from two different standards, and the names used to describe them refer to only the trade size and schedule. The 3/4 NPS opening is visibly larger than the 7/8 UNF opening. There are two different high-pressure steel SCUBA Tanks in wide use, the newer 3442 psi cylinders with 3/4 NPS threaded opening and the older 3500 psi cylinders with 7/8 UNF threaded opening. Also, Luxfer recently introduced a limited production run of 106 cubic foot capacity SCUBA cylinders that are a composite design: aluminum shell with fiberglass hoop wraps. This cylinder has a service pressure of 4350 psi and 7/8 UNF neck threads.

So how do you figure out what you have? Assuming your cylinder was manufactured exclusively for the North American SCUBA market in the last 50 years or so, look at the SCUBA Tank neck for the DOT stamp. If it reads DOT-3AL or DOT-3AA it almost certainly has a 3/4 NPS threaded neck opening. (3AL means aluminum, 3AA means steel.) If it reads DOT-Xxxxx-3442 it's a steel cylinder, also with 3/4 NPS threaded opening. If it reads DOT-Xxxxx-3500 or DOT-Xxxxx-4350, it's a steel or composite cylinder with a 7/8 UNF threaded opening. (The Xxxxx is a manufacturer specific four or five digit exemption number that starts with the letters E or SP.) Another test, if the valve is out of the cylinder, is that a U.S. quarter coin will fit through the 3/4 NPS cylinder neck opening but will not fit through the 7/8 UNF opening.

If your cylinder is not designed for use in recreational SCUBA or is very old, it probably also has an incompatible neck thread form. There are also some extremely rare small cylinders used for inflation and rebreather diving applications that use special valves not commonly seen in SCUBA. SCUBA cylinders manufactured primarily for the European market have either "M18X1.5" or "M25X2" ISO metric neck threads which look similar but are NOT compatible. If you are unable to determine the neck thread form of your cylinder with absolute certainty, consult a local cylinder inspection and testing facility because mismatched threads are very dangerous.



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