Configuration Options

42b-52b baratron flow-through pressure switch 52C Pressure Switch, 10-26,000 Torr, Flow-Through, Referenced to Vacuum


  • Type
    Vacuum/pressure Switch
  • Configuration
  • Pressure Range Full Scale
    10 Torr through 500 psi
  • Fitting Type
    4 VCR® male
  • Accuracy
    ±0.5% of Full Scale (± temperature coefficient)
  • Trip Point Range
    5-100% of Full Scale
  • Trip Point Dead Band
    ±3% of Full Scale
  • Response Time
    <20 msec
  • Internal Volume
    6.6 cc
  • Temperature Coefficient
    ±0.07% of Full Scale/°C
  • Materials Exposed to Process Gases
    Inconel and 316L stainless steel
  • Overpressure
    2 x Full Scale or 45 psia, whichever is greater
  • Power Requirements
    10-20 VDC @ 35 mA max. or 20-30 VDC @ 30 mA max
  • Ambient Operating Temperature
    Electromechanical relay - SPDT (isolated) contacts rated up to 1 Amp @ 30 VDC resistive
  • Compliance
    CE, UL recognized* (cULus E520864), EN/IEC CB Approved to all National Deviations *standard MKS part numbers only


Baratron® Capacitance Manometer Technology

Capacitance manometers are electro-mechanical gauges that can measure both pressure and vacuum. The capacitance gauge translates a pressure-modulated movement in a thin diaphragm into an electrical signal proportional to the pressure. The pressure sensor is the thin diaphragm that is exposed to the pressure or vacuum being measured via the inlet tube. An electrode is mounted in the reference cavity behind the diaphragm. Pressure differences between the process and the reference cavity deflect the diaphragm slightly, changing the distance between it and the electrode. Variations in this distance produce variations in the capacitance between the diaphragm and the electrode creating an electrical signal that is proportional to the pressure change. Since differences in the capacitance signal are produced by physical changes within the manometer and not by changes in the gas properties, pressure measurements by the capacitance manometer are independent of the composition of the gas being measured.

Capacitance manometer sensor schematic showing the internal components

Absolute Pressure Switching

51 and 52 pressure switches are referenced to vacuum for absolute pressure trip point switching. Applications for absolute pressure switches include soft pumping, gas box switching, and safety interlocks.

Factory Set Trip Point

The relay trip point is factory set from 5% to 100% of the Full Scale pressure range. This means there is no need for personnel to adjust the set point and no safety concerns from an erroneously adjusted set point.

Fail-Safe Relay Operation

The relay mode on 41, 42, 51, and 52 switches can be set to either energize above or below the set point. If the unit loses power, the relay switches to the Normally Closed position. The user can indicate whether the Normally Closed position is above or below the set point. Using Energize Above the set point as an example, the relay is in the Normally Open position when the pressure is higher than the trip point and Normally Closed when the pressure is below the trip point. The scenario is reversed for Energize Below the set point option. In vacuum systems, the fail-safe operation is if the system loses power causing the relay to de-energize, the relay is in the same state as the high pressure condition. Therefore, most vacuum systems require the relay energize with pressure decreasing or below the set point.

The 41B, 42B, 51B and 52B Vacuum and Atmospheric Pressure Switches provide increased accuracy over mechanical type switches, thereby providing tighter control and repeatability of process, improving throughput and yield.

9-pin Type “D” Pinouts

Pin Description
1 Power Return (-)
2 Power Input (+)
3 Relay NO Contact
4 Relay Common
5 Relay NC Contact
6 Unused
7 Unused
8 Unused
9 Chassis Ground

Flying Lead Wiring

Wire Description
Red Power Input (+)
Black Power Return (-)
Green Relay NO Contact
White Relay Common
Orange Relay NC Contact
Bare Wire Chassis Ground

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