Liquid Level Switch Selection Guide

Having difficulty finding exactly what you need? Our liquid level switch guide can help you find exactly what you need. Whitman Liquid Level switches come in a number of sizes and materials for use in a variety of industrial applications and other end-user solutions.  The full line of quality liquid level switches are factory-sealed to NEMA 6 rating specifications using our “Red Seal” potting compound. This compound is installed at the factory and allow our switches to be subjected to conditions far more demanding than those offered by our competitors.

The below chart gives an overview of our product catalog at Whitman, and the functionality of each of our switches. Depending on your minimum liquid specific gravity, wetted materials, temperature range, and maximum system pressure, you will find a switch that will meet your specific needs and exceed your expectations. 

Steps Required for Identifying the Right Liquid Level Switch for your Application:

The below commentary outlines all the steps needed in identifying the right pressure switch for your applications. If you are confused by any of the terminology or have additional questions, please reference our Switch Glossary or reach out to our engineering team at [email protected]:

Step 1: Determine your Liquid Specific Gravity

Liquid specific gravity is the single most important consideration when specifying a liquid level switch as it will determine if your level floats or sinks. It is the ratio of the mass of the liquid to the mass of an equal volume of water at a standard temperature, typically 60℉. Liquids with a specific gravity less than one will float on water, while those greater than one will sink. Each Whitman level as a minimum liquid specific gravity under specifications.

Step 2: Select a float that is compatible with your Liquid

We offer a number of wetted materials including Brass/Buna, stainless steel, CPVC plastic, Kynar plastic, and polypropylene. It is imperative to check for chemical compatibility of the switch to the liquid in your application whether it be oil, water, or acetone among others. Both stainless steel and CPVC work well in water (among others), while a buna (nitrile) float is ideal in hydraulic oil as it is a specific for petroleum products.

Step 3: Identify your Maximum System Pressure

If your level switch is ending up in an enclosed system, the maximum system pressure must fall below the level switch’s “Crush Pressure.”

Step 4: Select an Optimal Mounting Orientation

There are two basic mounting types: Horizontal or Side-Mounted and Vertical or Top-Mounted.

Side Mounted level switches typically screw into the sides of tanks with an NPT thread but can be mounted with a “Bulkhead” straight thread and a gasket or o-ring. Both NPT and Bulkhead units are typically reversible and probably have NO or NC (Normally Open or Normally Closed) stamped on them.

The most popular of these is the ½” NPT male fitting. This allows the entire properly designed assembly to be feed through a ½” NPT female port without the mess and hassle of taking the top off your tank to do inside installation. 

Top Mounted level switches are the work horses of the industry. They attach to the covers or brackets of liquid containers like tanks, vats and drums. They come in a remarkable assortment of materials to match various applications including Stainless Steels, Polypropylene, CPVC, Kynar plus Brass / Buna.

Bent level switches are vertical acting switches that mount on side walls. These are especially handy when there is no top to mount to. They come with NPT and Bulkhead fittings.

Multi-level Custom Vertical Switches are the most versatile in the industry. If you have a need for multiple height notification such as alarms or process starting and stopping such as fill pumps, this is the switch you want. They come in single shaft design with up to 6 levels. As these are purely custom, Whitman can provide any material, wiring, and attachment fitting desired.

Temperature-Level Vertical Switches are all the above with the addition of a temperature switch inside the level switch tube.


Step 6: Determine your ideal Fitting

The majority of our liquid level switches come with either a 1/2” NPT or a 1/8” NPT fitting. But many customers require a 1/2” or 1/8” BSPT fitting or a 3/8”- 24 UNF  2A threat, all of which are available.

Step 7: Select any Additional Options

At Whitman, we allow the end-user any number of additional add-ons to improve switch functionality while limiting the steps necessary between ordering of a switch and installing it in your application. Our additional add-ons include:

Bar Code

Customer P/N on label

Loctite Vibraseal on fitting

Interfaced floats

Alternate Wiring and Cabling


Wire Tags

O-Rings for straight thread units

Wire Connectors

Special Packaging Instructions

Teflon Tape on Fitting

Next in-line fee


Quality at Whitman is proven both by a reliability rate substantially higher than industry standards and an ISO 9001 certified Quality Management System. This is fostered both by the uncommon capabilities of our sales personnel who seek detailed application information before recommending the proper model, and by the feedback from our technical people who continually test our products in a variety of conditions over lengthy periods of time.

We appreciate your interest in our line of products, and we are confident that our switch performance will exceed your expectations.