Pressure Washer Rupture Discs

A rupture disc is the last safety device standing between a runaway hot water machine and a burst coil. When system pressure climbs past the disc rating, the disc bursts and vents water before something expensive lets go. Sun Brite Supply carries replacement rupture discs in 7000 and 8000 PSI ratings. Call 301-519-9274 and we will match a disc to your machine before you order.

How to Pick the Right Rupture Disc

Match three things and you cannot go wrong: the burst pressure rating, the temperature rating, and the thread size. Most hot water skids take a 7000 PSI disc rated to 225 degrees F, while some higher pressure coils call for 8000 PSI. Our discs come with 3/8 inch MPT or 1/2 inch MPT inlets, so check the port on your coil before ordering. Never install a disc rated above what the machine builder specified. A higher rating defeats the whole point of the part.

A Blown Disc Is a Symptom, Not the Problem

Rupture discs do not wear out on a schedule. They burst because something else failed. The usual suspects are a burner that keeps firing after the trigger closes, a stuck unloader, a bad thermostat or pressure switch, or a plugged nozzle that spiked the system. Screw in a new disc without finding the cause and you will blow that one too. Check the burner controls and the unloader first, then replace the disc. The part costs less than the coil it protects, and far less than the downtime.

What We Carry

The Suttner 8000 PSI rupture disk with 3/8 inch MPT inlet runs $43.00. The 7000 PSI disc rated to 225 degrees F with 1/2 inch MPT inlet is $64.62. Both are call-ahead items, so phone us and we will confirm availability and lead time before you commit.

Related Parts

• Thermal relief valves
• Safety relief valves
• Pressure relief valves
• Check valves
• Unloader valves
• Burner parts
• Hot water pressure washers
• Our Gaithersburg, MD counter

Frequently Asked Questions

Why did my rupture disc burst?

Something upstream failed. The most common causes are a burner that keeps heating after the gun closes, a stuck unloader, a failed thermostat, or a blocked nozzle. Find and fix the cause first or the new disc will burst too. Rupture discs do not fail from normal use.

Can I plug the rupture disc port instead of replacing the disc?

No. The disc is there to vent a dangerous pressure spike before the coil or a fitting fails. Plugging the port removes the machine's last layer of overpressure protection and puts the operator at risk. Replace the disc with one of the same rating.

What pressure and temperature rating do I need?

Use the rating the machine builder specified, never higher. Most hot water pressure washers use a 7000 PSI disc rated to 225 degrees F. Some higher pressure coils call for 8000 PSI. Check your manual or call us with the model number and we will look it up.

Where is the rupture disc located on a hot water pressure washer?

It threads into a port on or near the heating coil outlet, inside the coil housing on most skids and trailer rigs. Follow the discharge plumbing from the coil and look for a small hex body with a vent outlet.