Mercoid Series DA

Operating Requirements D is the generic designation for the pressure switch series. The聽next letter following the D designates the function of the switch聽with regard to the type of deadband and operation. DA, for example,聽means a D series pressure switch that has an adjustable deadband聽with double adjustments and is fully automatic. See page 10聽for more information.

Enclosures A general purpose NEMA 1 enclosure is furnished as standard on聽all Series D pressure switches. Weatherproof and explosion-proof聽housings are optionally available and designated by adding a third聽character to the model number. DAW, for example, indicates a DA聽pressure switch with a weatherproof enclosure.

Wetted Material The D Series is available with Bourdon tubes constructed of brass,聽Type 403 stainless steel, and Type 316 stainless steel. Material is聽designated as part of the series type number with 3 corresponding聽to brass, 2 to 403 stainless steel, and 4 to 316 stainless steel. For example,聽DA-31, DA-7031, DS-7231, and DA-531 all have brass bourdon聽tubes.

Switch Type and Action Mercoid庐 Series D pressure switches are available with mercury or聽snap-action contacts. Snap-action switch models always start with聽the series type number of 7. For example, DA-7031 and DS-7231聽are both snap switch models. Snap switches are availale in SPDT聽and DPDT while the mercury switches are available in SPST,聽SPDT, DPDT, and DPST. The switch code designates the type of聽contact and follows the series type number in the overall model聽number. For example, DA-7031-153 is a SPDT snap switch while聽DA-31-153 is a SPDT mercury switch. Contact rating should also be聽considered when choosing the contact type.

Operating Range The last part of the Series D model number is the operating range聽number. Operation of the switch is adjustable within the limits of聽the shown operating range. The upper limit of the adjustable operating聽range is also the maximum pressure for the switch and聽should not be exceeded. For example, DAW-33-3-2 has range number聽2, which is 0 to 30藵 Hg vacuum.