Tuesday, November 21, 2017

How To Order

How to Choose the Proper Pressure or Vacuum Switch


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

·       Type of Media being sensed

·       Maximum System Pressure

·       Amperage

·       Set Point/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.

To gather the most accurate information, we suggest the customer review the



                by clicking the link here or at the bottom of this page.

 After reviewing the form, please contact us or one of our Representatives listed under the Rep tab in the title bar above. We will be 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:

MEDIAWhat 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 PRESSUREWhat 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?

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.

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.

SET POINT- 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.

  Miniature Pressure Switch Series Offerings



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.


Standard Electrical Interfaces

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.