High Pressure Low Set Point Pressure Switches

Product Announcement from Whitman Controls Corporation

J205G High Pressure/Low Set Point Pressure Switch
The J205G High Pressure Low Set Point Pressure Switches are among our most versatile offering, affording the end user an extensive operating environment and a wide range of set point optionality.
Set Point Range: 0.80 to 800 PSIG
Max System Pressure: 5,000 PSIG
Temperature range: -65°F to +225°F (-54°C to +107°C)

How Do I Find The Right Pressure Switch?
Selecting a pressure switch that is well suited for a particular application is a multi-faceted process. The trick is to know what questions to ask to optimize your application.

Pressure and vacuum switches have been around for at least 100 years and are considered well- established, end-sensor technology. It is, therefore, surprising how many potential users don't know the fundamental considerations of specifying one of these devices.

There are six major categories you need to explore to specify a pressure or vacuum switch. They are in relative order of importance:

  • System pressure
  • Set points
  • Environmental conditions
  • Electrical operating parameters
  • Media port interface characteristics
  • Special requirements

System Pressure
Maximum system pressure is probably the most important parameter you have to consider when choosing a pressure or vacuum switch. So the first step is to determine the application's maximum and normal system pressures. This is necessary even if you plan to use a vacuum switch.

Be aware of the big picture. Certain situations obscure the fact that you have high system pressures. Some applications normally run in a vacuum, but still experience major positive pressures, such as a vacuum chamber that can have major pressure inrush spikes. Other applications have low gauge set points and major positive pressures. For example, you may have a switch downstream of a solenoid valve. In this situation, you have short-duration pressure spikes that may not show up on a pressure gauge. Still, others have high set point requirements and high system pressures, such as a hydraulic system. In each of these examples, a different switch is called for. Choose a pressure switch that will survive and thrive in the maximum system pressure.

Set Points
You usually have a reasonable idea of your application's desired set point, but there are several important questions that accompany it. For example, is the set point on increasing pressure (or vacuum) or decreasing pressure (or vacuum)? Do you want the switch to open or close when it reaches its set point, or do you need a single-pole-double-throw switch?

Other questions arise concerning set point adjustability. For example, do you require field adjustability? Usually, this is desirable when you do not know the set point or wish to experiment. Field adjustability with a factory preset switch is suitable when you know your set point but want field adjustability. And a factory pre-set switch with a fixed set point is usually found in OEM applications where it is not appropriate for the end user to readjust the set point

You should also take into account:
Do you need a switch with a fixed differential between "on" and "off" or a calibrated switch? Using one switch to do both the "on" and "off" functions at two different set points can save money and circuitry.

What is the anticipated frequency of operation? All devices have a maximum frequency of operation. Make sure the pressure or vacuum switch can meet or exceed this.

Environment Conditions
The pressure or vacuum switch's environment consists of the media that it senses and the external environment in which the device functions. Pay attention to the media—the normal operating temperature expected temperature extremes, and contaminants present. This information will aid in selecting the wetted material for the switch. Wetted materials are the materials of construction that your process media will actually be in contact with (e.g., air, water, acid, or hydraulic fluid).

Regarding the external environment, determine if it is an indoor or outdoor application. Will the switch be in a control panel box or exposed to the elements? Is a NEMA-class enclosure required? What are the expected environmental temperature extremes and the normal temperatures? Also, decide if shock and vibration will be factors in the application. Weighing all these factors will allow you to make a more enlightened choice.

Electrical Operating Parameters
The electricity you run through the pressure or vacuum switch varies with the application. Determine the amount of voltage supplied to the device. Is the voltage AC or DC? Is it inductive, resistive, or capacitive? Find out where the electricity passing through the switch's electrical interface is going and what it is doing. For example, if it is running a relay, the electricity will be inductive and have electrical inrush spikes that have to be taken into account when specifying the electrical rating. Also, it's important to quantify the amperage. Amperage is especially important because you typically choose gold contacts for light current and silver contacts for heavy current.

Additional questions to ask: What kind of electrical interface you want to use? Do you want wires, terminal blades, screw terminals, DIN connectors, military-style connectors, or another type?

Media Port Interface Characteristics
What size (e.g., 1/8 in.) and type (e.g., NPT or VRC) fittings do you prefer? Remember 1/8 in. and 1/4 in. NPT are industrywide default pipe threads. Some applications, however, require special media connections, such as 1/4 in. VCR for high-purity applications, or other specialty connections that almost always cost more money. Specials are usually worth considering.

Downloadable Catalogs


Having difficulty identifying the right switch for your application? 
Reference our Pressure, Vacuum, and Liquid Level Switch Selection Guides below. With a limited number of inputs, you'll be well on your way to finding a switch that helps you and your application maximize performance. At Whitman Controls, our extensive selection of switches provide ultimate versatility across a wide range of operating environments.

Pressure Switch Selection Guide

Vacuum Switch Selection Guide

Liquid Level Switch Selection Guide


About Whitman Controls
Whitman Controls specializes in the manufacture of miniature pressure, vacuum, temperature, and liquid level switches. The company prides itself on the diversity and quality of its product offering, proven by its ISO 9001 certification and the industry leadership position the firm has held for over 40 years. As a Service-Disabled Veteran-Owned Small Business, we believe in applying the same principles of military service to our every day practices: tireless dedication, rigorous standards of quality, and faithfulness to our values and mission. This translates into providing a quality product with superior service to exact customer specficiation and always exceeding our customers' expecations.

Whitman is built on our extensive offering of high quality, customized switches. We can build and ship a switch to your exact specifications in two weeks or less, with overnight shipping on in-stock models! Don't choose a competitor switch with inferior versatility and performance when we can take into account your application, media environment, and dozens of other specifications to meet all your performance needs and surpass your expectations.

At Whitman we are fiercely committed to our clients, particularly those who have been loyal partners for the entirety of our 40+ years of existence. Most importantly, we never lose sight of the core values upon which Whitman was built: high quality products with an unrelenting focus on customer service. Thank you for your commitment and loyalty to Whitman Controls over the years. If you have any questions, we encourage you to contact us directly at 860-583-1847 or info@whitmancontrols.com.

We look forward to building our partnership with you.