The oil pressure in these motors is carried at ten pounds, a relief valve being fitted to hold the pressure constant.
At R is the condenser relief, at U the relief valve for the water chambers.
I became aware of the soft, continuous popping sounds of the air-bubbles escaping from the relief valve of the head-piece.
A similar test over an equal period may then be conducted with the relief valve not water-sealed.
Nor is it less important that careful attention be given to the setting and operation of the relief valve, as will be seen later.