The design of these switches is based on the well-known

operation. MKS has utilized this capacitance technology

for more than three decades and it remains the most

stable, accurate, and reliable sensor available today. The

pressure switches sense the deflection of a diaphragm

due to applied pressure, providing a switched output

when pressure exceeds or drops below the chosen set

point. The dual electrode sensor is an all-metal, all-welded

design, thus exposing only corrosion-resistant 316L

mated to sophisticated electronics to further optimize

performance. The resulting enhanced accuracy and long-

term stability yield a switch with unparalleled repeatability.

The relay mode on 41B, 42B, 51B, and 52B 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, Atmospheric and

Pressure Switches provide increased accuracy over

mechanical type switches, thereby providing tighter control

and repeatability of process, improving throughput and

yield.

Dimensional Drawing: Single Ended—

Note: Unless otherwise specified, dimensions are nomi-

nal values in inches (mm referenced).

Output Connections

9-pin Type “D”

Flying Leads

1.

Power Return (-)

Red - Power Input (+)

2.

Power Input (+)

Black - Power Return (-)

3.

Relay NO Contact

Green - Relay NO Contact

4.

Relay Common

White - Relay Common

5.

Relay NC Contact

Orange - Relay NC Contact

6.

Unused

Bare Wire - Chassis Ground

7.

Unused

8.

Unused

9.

Chassis Ground

Low Pressure (1000 Torr and lower)