Operator TrainingShear Valves

South Carolina Department of Health

and Environmental Control

Shear Valves

Shear Valves are required per 280. 20 on all pressurized piping lines and must be installed in accordance with industry standards and manufacturer specifications. Suction systems are

exempt from this requirement.

Shear Point

Connects to Dispenser

Connects to Piping

Spring Loaded Valve

Fulcrum Arm

Where pressurized piping comes into the dispenser a shear valve is installed. The shear valve stops releases when a dispenser is hit by a vehicle. It contains at least one valve which is spring-loaded to snap shut. Each shear valve has a shear point which is designed to break upon impact. When a dispenser is hit with enough force if the shear valve is anchored correctly, the valve(s) will close and the shear valve will break at the shear point. This creates two capped off parts of the piping that releases no fuel.

Shear Valves

It is important to ensure that a shear valve is anchored properly or it may not function correctly during an impact. Above are examples of shear valves correctly anchored according to manufacturer's specifications. The bolts are tight, the valve is firmly against the stabilizer bar and the stabilizer bar is rigidly anchored to the side walls of the dispenser. The following slides show examples of poorly installed shear valves.

Shear ValvesShear valves must be anchored. This is an example of a shear valve that is not anchored. It is missing a stabilizer bar as well as any connections to the dispenser.

Where is the anchor??

Shear ValvesAll bolts must be tight. If there is a place for a bolt then there must be a bolt and it must be tight. If the bolt is missing or loose the

shear valve may not function properly during an impact.

Loose BoltsMissing Bolt

Loose Bolt

Shear ValvesWhen anchored to a face plate, the face plate must also be securely anchored. If a face plate is part of the manufacturer’s specifications then it must be installed and remain flush with the stabilizer bar.

Stabilizer Bar

Gap Between Face Plate and Stabilizer Bar

Shear ValvesShear valve should be flush against the stabilizer bar. For the U-Bolt design, the U-Bolt should sit properly in the designated grooves of the shear valve.

Gap Between U-Bolt and Stabilizer Bar

Groove

Groove

U-Bolt

Shear ValvesSome shear valves are designed to be anchored with a channel iron. A channel iron should be used if a C-beam cross bar and U-bolt are used.

C-Beam Cross bar

Correctly installed channel iron Missing

channel iron

Shear ValvesIf there is no dispenser pan to secure a stabilizer bar to then a retro-fit bracket can be installed. A retro-fit bracket should dig fully (not just touching) into the concrete to be secure.

Retro-fit bracket not dug into concrete

Retro-fit bracket

Shear ValvesThere should be enough clearance for the fulcrum arm to rotate completely. The fulcrum arm is made of soft metal that will break if it comes in contact with anything during its rotation. If the fulcrum does not rotate the shear valve will not close off and petroleum could be released.

Fulcrum arm cannot make full rotation

Fulcrum arm

Shear Valves

These two pictures (showing the same shear valve) are an example of what can happen if the shear valve is not anchored correctly. The channel iron was not installed properly. The dispenser got hit, putting pressure on the piping. The two sections of the stabilizer bar separated allowing the nuts and washers to pull through. Had this been a more serious hit, the nuts and washer could have pulled all the way through, the shear valve would not have sheared properly, and the piping could have broken causing a release of fuel.

Shear Valve After Impact-Minor

Shear Valves

This picture shows a dispenser that has been completely knocked over and the shear valve did not shear at all due to improper installation. The piping was pulled out of the ground and broke below the shear valve. A release and a fire were the results of this impact.

Shear Valve After Impact-Major

Remnants of Dispenser

Shear Valve