MIL-T-19646A

THERMOMETER, GAS ACTUATED, REMOTE READING

Year: 1990

Abstract: This specification covers environmentally hardened thermometers which utilize an elastic element to measure the pressure within a gas filled closed system (thermal system) and convert this pressure to an analog temperature indication on a circular dial. Remote reading is accomplished by connecting the analog temperature indicator to the thermometer bulb by a specified length of capillary tubing. The gas actuated thermometer bulb is configured for either direct immersion or insertion into a thermowell.
Gas actuated thermometers shall be classified according to the following variables, as specified (see 6.2):
(a) Sensor configuration (see 1.2.1).
(b) Range (see 1.2.2).
(c) Dial size (see 1.2.3).
(d) Capillary tubing length (see 1.2.4).
The sensor configuration shall be designated by two symbols; the first symbol shall designate the class and the second symbol the subclass. The class, designated by the letter A, B, or C, identifies the sensor type and mounting method (see 3.3.2.1.1). The subclass, designated by a number, identifies the physical dimensions of the individual sensors. Class A has only one subclass and shall be designated as A1. Class B has six subclasses as shown on figure 1. Class C has four subclasses as shown on figure 2. Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to: Commander, Naval Sea Systems Command, SEA 55Z3, Department of the Navy, Washington, DC 20362-5101 by using the self-addressed Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter.
The range shall be designated by the sequence of symbols listed in table IV. The range shall be selected for a particular sensor configuration class only if that range is specified for the particular sensor configuration class in table IV.
The dial size shall be designated by one of the following symbols: 
                    Dial size                    Symbol                        3-½                         3                       4-½                         4                       8-½                         8


The capillary tubing length selected is designated by its numerical value in units of feet (see 3.3.2.2).
A specification-based PIN to identify sensor configuration, range, dial size, and capillary tubing length is included in section 6 (see 6.10).
Intended Use: This sensor configuration is intended for the application in which the sensor is installed in a mounting bracket. The mounting bracket is constructed in accordance with NAVSEA 810-1385917. This sensor configuration is intended to be used in applications where the air temperature is being measured at pressures of or near 1 atmosphere. This sensor configuration is intended to retrofit mercury actuated thermometers with the same sensor configuration in saturated and superheated steam applications. This sensor configuration is intended for retrofit and replacement applications only and should not be used for new construction. This sensor configuration is intended for application in which the sensor is inserted into a thermowell. The sensor configuration is compatible with thermowells constructed in accordance with MIL-T-24270. The sensor configuration is not intended for applications requiring direct immersion into the process fluid or for applications where the sensor becomes part of the process system pressure boundary. Each temperature range is intended for use in the application or process fluid listed below: (a) −40 to 180°F range for colds storage (air). (b) 20 to 240°F range for water and oil. (c) 50 to 550°F range for hot water and compressed air. (d) 50 to 750°F range for saturated steam. (e) 400 to 1200°F range for superheated steam.
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