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Mercoid Series DA

Series DA/DS Bourdon Tube Pressure Switch

Mercoid Series DAPressure Ranges to 8000 psi (551.6 bar)

Customers tell us that this is the best pressure switch made. The Mercoid Series DA / DS is one of the world’s broadest lines of pressure switches. Whatever your application might be, it is most probable it can be fully satisfied with a D Series pressure switch.

The D Series has extremely high sensitivity and great repeatability. The Mercoid Series DA / DS are equipped with two external adjustments, one for setting high pressure operating point, the other for setting low pressure operating point. Deadband, the difference between high and low set points, is adjustable over the full scale. The DS Models are equipped with a single external adjustment for setting operating point only. The deadband is fixed at a factory setting and cannot be altered in the field. For switches choose between the snap action switch, hermetically sealed snap action switch and hermetically sealed mercury switch.



Mercoid Series DA Specifications

  • Wetted Materials: Brass, 403 SS, or 316 SS.
  • Temperature Limit: 180°F (82°C).
  • Pressure Limit: Maximum pressure of the operating range.
  • Enclosure Options: General purpose, weatherproof or explosion-proof.
  • Repeatability: ±1% of full operating range, ±1.5% on DS-7300 models.
  • Switch Type: SPST mercury switch, SPDT mercury switch, SPDT snap switch, or SPDT hermetically sealed snap switch. Other circuit types available.
  • Electrical Rating: See Catalog page.
  • Electrical Connections: Screw terminal.
  • Conduit Connection: General purpose: 1/2″ hole for conduit hub. Weatherproof: 1/2″ conduit hub. Explosion-proof: 3/4″ female NPT.
  • Process Connection: General purpose and weatherproof: 1/4″ male NPT; 1/2″ male NPT on range 15S and 16S. Explosion-proof: 1/2″ male NPT and 1/4″ female NPT.
  • Mounting Orientation: Vertical.
  • Set Point Adjustment: Thumbscrew.Weight:General purpose: 4 lb (1.8 kg). Weatherproof: 6 lb (2.7 kg). Explosion-proof: 8 lb (3.5 kg).
  • Deadband: See Catalog page.
  • Agency Approvals: CE, CSA, FM, UL. (mercury switch units are not CE approved). (Consult factory for FM approval models.)


Mercoid Series DA Features

  • Visible calibrated dial.
  • On/off indication (except hermetically sealed snap switch models).
  • Adjustable or fixed deadband.
  • SPDT snap-action, hermetically sealed snap action or hermetically sealed mercury switch.
  • External switch setpoint adjustments.
  • Minimum deadband is obtainable at any point in the range.
  • Pressure Ranges of full vacuum to 8000 psig.
  • UL listed, CSA approved. Many models FM approved.
  • General purpose, weatherproof or explosion-proof enclosures.


Mercoid Series DAH
DAH Enclosure

Mercoid Series DA Options

  • Explosion-proof Enclosure (Series DAH): Suitable for Class I, Groups C and D; NEMA 7; Class II, Groups E, F, G; Class III NEMA 9 and 9A, Division 1. Add “H” to model number after DA or DS. Example: DAH-31-153-7.
  • FM Approved: For general purpose and explosion-proof models see Agency Approvals on Specification page. Add “F” to model number after DA, DS, DAH or DSH. Examples: DAF-31-153-7 or DAHF-31-153-7.
  • Other Options (consult factory): DPDT switches or other switch types, fixed deadband mercury switch units for low deadband applications, manual reset operation, two-stage operation, acetal bushed movement for applications with high amounts of vibration and/or pulsation, fungus proofing, siphon, diaphragm seals, mounting flange and remote connection.
  • Weatherproof Enclosure (Series DAW): Add “W” to model number after DA or DS and change 1 to 3. Example: DAW-33-153-7.



Available Series D Models

SPDT Mercury 4A @ 120V, 2A @ 240V Switch

DA-21-153-10S25-600 psigAdjust. 25 psig min403SS
DA-21-153-11S50-1000 psigAdjust. 60 psig min403SS
DA-21-153-12S100-1500 psigAdjust. 90 psig min403SS
DA-21-153-13S300-2500 psigAdjust. 150 psig min403SS
DA-21-153-15S500-5000 psigAdjust. 450 psig min403SS
DA-21-153-16S800-8000 psigAdjust. 750 psig min403SS
DA-21-153-25S30" Hg Vac-60 psigAdjust. 6 psig min403SS
DA-21-153-26S30" Hg Vac-75 psigAdjust. 8 psig min403SS
DA-21-153-5S2-60 psigAdjust. 4 psig min403SS
DA-21-153-6S5-100 psigAdjust. 6 psig min403SS
DA-21-153-8S10-200 psigAdjust. 8 psig min403SS
DA-21-153-9AS40-350 psigAdjust. 14 psig min403SS
DA-21-153-9S10-300 psigAdjust. 14 psig min403SS
DA-31-153-11/8-15 psigAdjust. 1 psig min403SS
DA-31-153-230-0" Hg VacAdjust. 2" Hg min403SS
DA-31-153-2725" Hg Vac-50 psigAdjust. 3.5 psig min403SS
DA-31-153-310" Hg Vac-12 psigAdjust. 1 psig min403SS
DA-31-153-3A1/8-20 psigAdjust. 1 psig min403SS
DA-31-153-41-35 psigAdjust. 1.75 psig min403SS
DA-31-153-52-60 psigAdjust. 3 psig min403SS
DA-31-153-65-100 psigAdjust. 3.75 psig min403SS
DA-31-153-75-150 psigAdjust. 6 psig min403SS
DA-31-153-810-200 psigAdjust. 8 psig min403SS
DA-31-153-910-300 psigAdjust. 12 psig min403SS
DA-41-153-11E100-1000 psigAdjust. 100 psig min403SS
DA-41-153-13E200-2500 psigAdjust. 210 psig min403SS
DA-41-153-21E30-400 psigAdjust. 30 psig min403SS
DA-41-153-22E75-800 psigAdjust. 75 psig min403SS
DA-41-153-23E5-75 psigAdjust. 3 psig min403SS
DA-41-153-24E10-150 psigAdjust. 6 psig min403SS
DA-41-153-26E30" Hg Vac-75 psigAdjust. 7 psig min403SS
DA-41-153-6E10-100 psigAdjust. 7 psig min403SS
DA-41-153-9E10-300 psigAdjust. 18 psig min403SS

SPST Normally Closed Mercury Switch 10A @ 120V, 5A @ 240V

DA-21-2-10S25-600 psig25 psig min, Adjust403SS
DA-21-2-11S50-1000 psig60 psig min, Adjust403SS
DA-21-2-12S100-1500 psig90 psig min, Adjust403SS
DA-21-2-13S300-2500 psig150 psig min, Adjust403SS
DA-21-2-15S500-5000 psig450 psig min, Adjust403SS
DA-21-2-25S30" Hg Vac-60 psig6 psig min, Adjust403SS
DA-21-2-26S30" Hg Vac-75 psig8 psig min, Adjust403SS
DA-21-2-5S2-60 psig4 psig min, Adjust403SS
DA-21-2-6S5-100 psig6 psig min, Adjust403SS
DA-21-2-8S10-200 psig8 psig min, Adjust403SS
DA-21-2-9AS40-350 psig14 psig min, Adjust403SS
DA-21-2-9S10-300 psig14 psig min, Adjust403SS
DA-31-2-11/8-15 psig1 psig min, Adjust403SS
DA-31-2-20-30" Hg Vac2" Hg min, Adjust403SS
DA-31-2-2725" Hg Vac-50 psig3.5 psig min, Adjust403SS
DA-31-2-310" Hg Vac-12 psig1 psig min, Adjust403SS
DA-31-2-3A1/8-20 psig1 psig min, Adjust403SS
DA-31-2-41-35 psig1.75 psig min, Adjust403SS
DA-31-2-52-60 psig3 psig min, Adjust403SS
DA-31-2-65-100 psig3.75 psig min, Adjust403SS
DA-31-2-75-150 psig6 psig min, Adjust403SS
DA-31-2-810-200 psig8 psig min, Adjust403SS
DA-31-2-910-300 psig12 psig min, Adjust403SS
DA-41-2-11E100-1000 psig100 psig min, Adjust403SS
DA-41-2-13E200-2500 psig210 psig min, Adjust403SS
DA-41-2-21E30-400 psig30 psig min, Adjust403SS
DA-41-2-23E5-75 psig3 psig min, Adjust403SS
DA-41-2-24E10-150 psig6 psig min, Adjust403SS
DA-41-2-26E30" Hg Vac-75 psig7 psig min, Adjust403SS
DA-41-2-6E10-100 psig7 psig min, Adjust403SS
DA-41-2-9E10-300 psig18 psig min, Adjust403SS

SPST Normally Open Mercury Switch 10A @ 120V, 5A @ 240V

DA-21-3-10S25-600 psig25 psig min, Adjust403SS
DA-21-3-11S50-1000 psig60 psig min, Adjust403SS
DA-21-3-12S100-1500 psig90 psig min, Adjust403SS
DA-21-3-13S300-2500 psig150 psig min, Adjust403SS
DA-21-3-15S500-5000 psig450 psig min, Adjust403SS
DA-21-3-25S30" Hg Vac-60 psig6 psig min, Adjust403SS
DA-21-3-26S30" Hg Vac-75 psig8 psig min, Adjust403SS
DA-21-3-5S2-60 psig4 psig min, Adjust403SS
DA-21-3-6S5-100 psig6 psig min, Adjust403SS
DA-21-3-8S10-200 psig8 psig min, Adjust403SS
DA-21-3-9AS40-350 psig14 psig min, Adjust403SS
DA-21-3-9S10-300 psig14 psig min, Adjust403SS
DA-31-3-11/8-15 psig1 psig min, Adjust403SS
DA-31-3-20-30" Hg Vac2" Hg min, Adjust403SS
DA-31-3-2725" Hg Vac-50 psig3.5 psig min, Adjust403SS
DA-31-3-310" Hg Vac-12 psig1 psig min, Adjust403SS
DA-31-3-3A1/8-20 psig1 psig min, Adjust403SS
DA-31-3-41-35 psig1.75 psig min, Adjust403SS
DA-31-3-52-60 psig3 psig min, Adjust403SS
DA-31-3-65-100 psig3.75 psig min, Adjust403SS
DA-31-3-75-150 psig6 psig min, Adjust403SS
DA-31-3-810-200 psig8 psig min, Adjust403SS
DA-31-3-910-300 psig12 psig min, Adjust403SS
DA-41-3-11E100-1000 psig100 psig min, Adjust403SS
DA-41-3-21E30-400 psig30 psig min, Adjust403SS
DA-41-3-22E75-800 psig75 psig min, Adjust403SS
DA-41-3-23E5-75 psig3 psig min, Adjust403SS
DA-41-3-24E10-150 psig6 psig min, Adjust403SS
DA-41-3-26E30" Hg Vac-75 psig7 psig min, Adjust403SS
DA-41-3-6E10-100 psig7 psig min, Adjust403SS
DA-41-3-9E10-300 psig18 psig min, Adjust403SS

SPDT Snap Switch, Adjust Deadband

DA-7021-153-10S25-600 psig67.5 psig min, Adjust403SS
DA-7021-153-11S50-1000 psig142.5 psig min, Adjust403SS
DA-7021-153-12S100-1500 psig195 psig min, Adjust403SS
DA-7021-153-13S300-2500 psig390 psig min, Adjust403SS
DA-7021-153-15S500-5000 psig1350 psig min, Adjust403SS
DA-7021-153-16S800-8000 psig2250 psig min, Adjust403SS
DA-7021-153-25S30" Hg Vac-60 psig18 psig min, Adjust403SS
DA-7021-153-26S30" Hg Vac-75 psig22.5 psig min, Adjust403SS
DA-7021-153-5S2-60 psig13.5 psig min, Adjust403SS
DA-7021-153-6S5-100 psig19.5 psig min, Adjust403SS
DA-7021-153-8S10-200 psig22.5 psig min, Adjust403SS
DA-7021-153-9AS40-350 psig30 psig min, Adjust403SS
DA-7021-153-9S10-300 psig28.5 psig min, Adjust403SS
DA-7031-153-11/8-15 psig6 psig min, Adjust403SS
DA-7031-153-20-30" Hg Vac13.5" Hg min, Adjust403SS
DA-7031-153-2725" Hg Vac-50 psig12 psig min, Adjust403SS
DA-7031-153-310" Hg Vac-12 psig6 psig min, Adjust403SS
DA-7031-153-3A1/8-20 psig6 psig min, Adjust403SS
DA-7031-153-41-35 psig7.5 psig min, Adjust403SS
DA-7031-153-52-60 psig9 psig min, Adjust403SS
DA-7031-153-65-100 psig13.5 psig min, Adjust403SS
DA-7031-153-75-150 psig24 psig min, Adjust403SS
DA-7031-153-810-200 psig24 psig min, Adjust403SS
DA-7031-153-910-300 psig37.5 psig min, Adjust403SS
DA-7041-153-13E200-2500 psig600 psig min, Adjust403SS
DA-7041-153-21E30-400 psig78 psig min, Adjust403SS
DA-7041-153-22E75-800 psig180 psig min, Adjust403SS
DA-7041-153-23E5-75 psig12 psig min, Adjust403SS
DA-7041-153-24E10-150 psig16.5 psig min, Adjust403SS
DA-7041-153-26E30" Hg Vac-75 psig15 psig min, Adjust403SS
DA-7041-153-6E10-100 psig15 psig min, Adjust403SS
DA-7041-153-9E10-300 psig42 psig min, Adjust403SS

SPDT Snap Switch, Fixed Deadband

DS-7231-153-11/8-15 psig1.5 psig fixedBrass
DS-7231-153-20-30" Hg Vac3" Hg fixedBrass
DS-7231-153-310" Hg Vac-12 psig1.5 psig fixedBrass
DS-7231-153-3A1/8-20 psig1.5 psig fixedBrass
DS-7231-153-41-35 psig1.5 psig fixedBrass
DS-7231-153-52-60 psig2 psig fixed Brass
DS-7231-153-65-100 psig2.5 psig fixedBrass
DS-7231-153-75-150 psig3 psig fixedBrass
DS-7231-153-810-200 psig4 psig fixedBrass
DS-7231-153-910-300 psig5 psig fixedBrass

SPDT Hermetically Sealed Snap Switch

DS-7331-153-11/8-15 psig3 psig fixedBrass
DS-7331-153-20-30" Hg Vac5" Hg fixedBrass
DS-7331-153-52-60 psig3 psig fixedBrass
DS-7331-153-65-100 psig3.75 psig fixedBrass
DS-7331-153-75-150 psig5.25 psig fixedBrass
DS-7331-153-810-200 psig6.75 psig fixedBrass
DS-7331-153-910-300 psig9 psig fixedBrass


How To Order

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

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

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

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

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