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Relay Pump Operations: Who Says It's Just for the Long Lay?

Paul Shapiro

The use of the HRV, as with any water flow appliance, will have friction loss within itself that will have a direct affect on the flow potential for the operation. There are different designs of HRVs. Some have more pronounced friction loss in the supply line mode (no pump at the hydrant, hydrant pressure only) and others in the relay pump mode (pump at the hydrant to set up in relay), while others have friction loss in both modes.

The flow tests will reveal what I consider to be an insignificant flow loss in the HRVs, which is well worth the trade off when you consider what the HRV allows us to do, which is hooking up to an existing supply line without shutting the hydrant down.

The initial supply line is laid from the hydrant using the Humat valve.

Las Vegas Engine 4 using the Humat valve in a relay pump operation