Dry Fire Hydrant Design 28 - Connection Stress
 
By President Mark Davis
May 28, 2020
 

One of the common issues with dry fire hydrant design and installation is creating too much suspension of the suction hose when the pumper is connected to the dry fire hydrant. Ideally, suction hose should have at least one point of ground contact while the pumper is drafting. This point of contact takes some of the load off of the suction hose coupling which can be prone to leaking...especially when using lightweight suction hose.

Contributing to this problem can be the design of the dry fire hydrant. The "white" DFH shown in this news story is a bad design in terms of creating stress on the DFH fitting and the suction hose coupling. The actual suction head is located at the end of a big lever. The weight of the connection once the hose is filled with water places enough stress on the coupling to cause an air leak that in turn affects drafting. We are pretty sure that the DFH was built with good intentions; however, not with the best design.

The better choice when deciding to use a 90-degree piping set up is to use a 90-degree suction head as shown on the "yellow" DFH shown in the other photo. The 90-degree suction head provides a much more sturdy connection and thus, should reduce the opportunity for an air leak. In addition, the lower the suction head is located to the ground, the less the load placed on the fitting when the suction hose is connected.