The Hart system is designed for use with small groups of birds in cages or small pens. The birds drink from a cup which has a trigger. The birds push the trigger and water flows as required. Between uses the small amount of water may dry completely, so these trigger cups are also called dry cups. There are several different cups for different applications and two main mounting systems.
One system uses rigid white PVC pipe known as Pressure pipe. The cups are mounted on saddles which are glued in the required location. Several types of saddles are available. The other mounting system uses flexible pipe and saddles which clip onto wire or screw to the wall.
These cups are ideal when there is a large number of pens all on the same level. These cups use water pressure to shut the valve, so water pressure settings are very important. The ideal water pressure is 3 psi, equivalent to about 1.5 metres of water head. The limits are minimum of 1 metres, maximum of 2 metres of water head. The ideal way to provide this is using a regulator MPR-6003.
The drinker C20XL with C35P saddle has proved to be an effective cup for squabs.