Legend Valve & Fitting, Incorporated Technical Bulletin Regarding the ASSE 1019 Hydrant Types

This bulletin addresses questions regarding the differences between Frost Resistant Hydrant types as

called out in ASSE 1019.

 

A question that we have fielded from contractors through Legend customer service or Legend representatives

has been their misunderstanding of the function of the back flow relief.  During the process of relieving

backpressure, excess water needs to vent out of the sillcock.  In the T-550A, the excess water is directed

down the stem to a weep hole located behind the handle.  The amount of excess water is small and the weep

hole is located safely away from the home and interior walls. This is by design and to meet specifications

stipulated by ASSE.

 

Most commonly, a connected garden hose while being used can create back flow when the end nozzle is turn

on and off. Therefore, that back pressure may be enough to push water up through the stem and then out of

the weep hole behind the handle. 

 

There are three distinct frost resistant hydrant types as called out in ASSE Standard 1019 - “Vacuum Breaker

Wall Hydrants, Freeze Resistant, Automatic Draining Type”.  Each of these certifications has subtle difference

as defined in ASSE 1019, Section 1.2 - Scope.

 

Type C devices protect against backsiphonage and backpressure and contain at least one mechanism to

protect against backpressure.  Type C devices also require that the hose be removed to protect against

damage and freezing.

 

Type A devices also protect against backsiphonage and backpressure and contain at least two mechanisms

to protect against and relieve backpressure.  At least one of the mechanisms must be a check valve.  Type A

devices also require that the hose be removed to protect against damage and freezing.

 

Type B devices also protect against backsiphonage and backpressure and contain at least two mechanisms

to protect against and relieve backpressure.  At least one of the mechanisms must be a check valve.  Type C

devices do not require that the hose be removed to protect against damage and freezing.

 

Key Differences between Type C and Type A devices:

• Type A devices have a minimum of two mechanisms for backpressure while Type C can be only one.

• Type A devices relieve backpressure.  Type C devices do not relieve the backpressure; they simply

    use a device to block it from backflow into the residential water system.

• Both Type A and Type C devices require the hose to be removed during storage to protect from

   damage and freezing.

 

Key Differences between Type A and Type B devices:

• Type B devices do not require that the hose be removed to protect against damage and freezing,

    otherwise the performance and requirements are identical between Type A and Type B devices.

 

The Legend Valve T-552 is certified as ASSE 1019-C

The Legend Valve T-550 is certified as ASSE 1019-A

 

If you have any further questions regarding this topic or any Legend Valve products, please feel free to

contact the Legend Technical Department at 800-752-2082.