36 
BULLETIN 894, TJ. S. DEPARTMENT OF AGRICULTURE. 
PRESSURE REGULATION. 
The water pressure must be nearly equal in each, of the cold-water, 
recirculating-water, and hot-water mains, otherwise the mixing 
valves will be able to take water only from the main having the 
highest pressure. The difference must not exceed 5 pounds in pres- 
sure at any time. A steady pressure is necessary for unitorn tem- 
perature control; for if the pressure fluctuates more than 5 pounds 
satisfactory control is not obtainable. 
Fig. 11.— Diagram of steam and water supply connections and fittings. Overhead supply. 
LEGEND. 
F. Cold-water supply. 
A. Thermostatic water mixer. 
B. Thermostat on steam supply to coils. 
C Supplies to coils. 
D. Steam jet supply. 
E. Recirculating water supply. 
G. Hot-water supply (when hot-water main is 
installed). 
H. By-pass for cold-water past mixer. 
I. Pipe thermometer for temperature of water to 
sprays. 
The pressure in the recirculated and hot-water mains should be 
controlled by a pump regulator installed on the steam supply to the 
pump and connected on the pump side of the strainer. The cold- 
water-main pressure should be controlled by a pressure-regulating 
