Ordering Guidance

How to Choose the Proper Pressure or Vacuum Switch


The key to making your pressure or vacuum switch selection is most likely defined by:

  1. Type of media being sensed

  2. Maximum system pressure

  3. Amperage

  4. Setpoint/desired activation point


Although these are key to determining the proper switch for your application there are some additional inputs that may need to be defined.


Please complete the product application worksheet to receive a quote:












If you complete and submit the Product Application Worksheet we will contact you via email soon. We're happy to assist you in selecting the proper switch series for your application. The following are a few basic requirements for selecting the proper pressure or vacuum switch:


MEDIA - What is the fluid or gas that is being sensed? This will allow Wasco to ensure the wetted parts of the pressure switch or pressure transducer/transmitter are compatible with the application.


MAXIMUM SYSTEM PRESSURE - What is the maximum system pressure that the pressure switch or pressure transducer/transmitter will be exposed to? Is the unit required to still be functional and accurate after exposure to the maximum system pressure?

  1. Proof pressure is the maximum pressure the unit will see and still be required to remain functional and accurate. The maximum proof pressure provides Wasco with the ability to determine how wide or small the dead-band will be for a pressure switch.

  2. Burst pressure is the maximum pressure the unit will be exposed to without any rupture of the unit. (Escape of application media) The unit will no longer remain functional and accurate.


SETPOINT - This is the specific point where your customer would like the pressure or vacuum switch to actuate at. Do they want it to actuate when the system is increasing (rising), or decreasing (falling) pressure?

RESET POINT - After the switch has actuated, there is a certain amount of “dead space” it takes to reset the switch. This is also known as the “dead band”, or the reset point range. The Value Series, High Overpressure Series, and the High Purity Series dead-band will be a function of the maximum system proof pressure and is not adjustable. Wasco has the ability to internally customize the reset point for the P6, P7, P10, P11, P12, and P14 Series during the manufacturing process.  This is not something that can be adjusted by the end-user.


ELECTRICAL CHARACTERISTICS - What is the maximum amperage at a given voltage that the electrical switch will receive? The electrical amperage capacity cannot be lower than the circuit amperage. The switch is supplied with 3 wires, Common, Normally Open, and Normally Closed. If this is a first time application, we suggest all three wires so you will have the option to Open or Close. Once a final determination is made, Wasco can then make a 2-wire interface or remain with a 3-wire.




Value Series – Brass and Stainless Fittings:


P110 Series - 1-500 PSIG max. / V110 Series - 1.6 - 29.5” HG max.

P500 Series - 2-500 PSIG max. / V500 Series - 2-29.5” HG max.

P550 Series - 0.5 - 15 PSIG max. Low-Pressure Switch


High Overpressure Series:


P325 Series – 400 - 6000 PSIG max.

P400 Series – 100 - 6000 PSIG max.


High Purity Series:


SP120 Series - 1-500 PSIG max. / SV120 Series 1.6-29.5” HG max.

UHP150 Series - 1-500 PSIG max. / UHP160 Series 1.6-29.5” HG max.


Differential Series:


TP700 Series 1-500 PSIG max. / TV700 Series 1.6-29.5” HG max.




W2/W3 - Wire Leads - Potted to full height for strain relief. Standard # 20 AWG wire X 12” long jacketed wire. Polyvinyl Chloride insulated.

L2/L3 - Wire Leads - Potted low profile style, flying leads only. Standard #20 AWG wire X 12” long. Polyvinyl chloride insulated.

F2/F3 - Screw Terminals - Potted with # 8-32 screw terminals.

Q2/Q3 - Quick Connect - Potted 1/4” blade terminals. Will accept arch less, spade connectors.

S2/S3 - Pins - Potted with .060” diameter pins. Will accept AMP #60789-2 pin receptacles.