MIL-DTL-3155 Valve, Temperature-Regulating Ventilation Heater, Steam Control, Naval Shipboard UseThis specification covers thermostatic-controlled steam valves for temperature regulation of shipboard ventilation heaters. These valves are of the self-operated type, requiring no separate power source such as electricity or compressed air.

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MIL-DTL-3155D(SH)

3.4.7.4.1 Throttling range. A 1 �F change in either direction of the thermostat set point of the ambient air

temperature shall be sufficient to start the valve poppet through its operating stroke and the operating stroke shall be

sufficient to ensure complete throttling or modulating operation. The throttling range between fully open and fully

closed shall not exceed 6 �F.

3.4.7.4.2 Thermostat tolerance. The thermostats shall be capable of operating the valve controlled from fully

open to fully closed with a change in air temperature at the thermostat bulb of not more than �3 �F from the

thermostat set point.

3.4.8 Bellows. Bellows shall be of the seamless type. The operating bellows of the steam valve shall be made

of nickel-copper or of phosphor-bronze and shall be protected from direct steam impingement by a shield.

3.4.9 Capillary tubing. The capillary tubing shall be covered throughout the entire length with an armor to

provide physical protection. Armor shall be brass, bronze, or corrosion-resistant steel so constructed that the

flexibility of the tubing will not be excessively reduced.

3.4.9.1 Capillary tubing length. The length of the capillary tubing between the bulb and operating bellows shall

be 10 feet for Type L and Type W thermostats and 25 feet for Type R thermostat.

3.4.10 Bulbs.

3.4.10.1 Bulb materials and lengths. Thermostat bulbs shall be constructed of brass or copper and the bulb

lengths shall not exceed the dimensions shown on figure 2.