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Flow switches are protection devices. Like flow sensors, they’ll warn you when flow rate is below or above the target range. Unlike flow sensors, though, flow switches initiate an action. They could turn on or shut down a pump, open or close a valve, or just light a warning bulb. How you use a flow switch is up to you.


There are two main flow switch types — the paddle design and the piston or shuttle design. The paddle design of a flow switch places a hinged or spring-mounted paddle in the liquid flow path. Media flowing at the target rate holds this in position. An increase or reduction in flow moves the paddle, and this is sensed by a small switch. — Shuttle-type flow switches place a small cylinder or piston in the path of the moving liquid. Embedded in this piston is a permanent magnet. A switch outside the flow path senses the magnet’s position. If the magnet moves too far one way or the other, the switch activates an output signal. The flow rate that activates the switch is known as the “set point.”


Use flow switches to warn of liquid flow problems such as a blocked filter, failing pump or defective valve. Any of these malfunctions could affect process consistency, lead to equipment damage, and even cause spills and leaks. — Pump staging is another common application. A change in flow beyond the set point could be used to shut down a pump or bring a second unit online. Used this way, flow switches increase operational efficiency and reduce costs. — Every process with flowing liquid can benefit from flow switch controls. Food and beverage, pharmaceutical, water treatment and chemical production are just a few industries that use flowing liquids. Cooling systems are a good example. A change in flow will affect heat transfer rate and lead to damaged or defective product.


Install fluid flow switches in your liquid handling process and, most of the time, you’ll never know they’re there. Yet, should a problem arise or the situation demand, they’ll spring into action. Flow switches protect equipment and people, guard against accidents, and help lower costs — but only if they work properly. — A poor-quality flow switch does more harm than good. It will either activate inconsistently — adding variability to your process along with annoying false alarms — or it will fail to work when needed. Avoid costly problems by investing only in high-quality flow switches from a trustworthy American manufacturer.


Flow switch applications are so numerous that it’s impossible to have one already engineered for every possible use. That’s why we offer custom design. Search our extensive product catalog for a flow switch meeting your needs. If none exists, let’s talk about a custom unit.


Skimp on your level switch and you’re flirting with disaster. Level switches trigger pumps, valves or alarms that prevent overfilling or draining. Whatever is in the tank, an American-made level switch from Thomas Products LTD provides safe and reliable liquid level indication.


A level switch consists of a float that rises and falls with the liquid in the tank. On reaching preset levels — full or empty — the float activates a switch. That sends a signal you use to operate a pump, valve or alarm. The side-mount liquid level switch is the least complex design. This looks like the ball valve found in a toilet cistern. More sophisticated models use one or more floats riding on a vertical shaft. Inside each float, there’s a permanent magnet. As it passes over a switch in the shaft, a signal is sent. Sometimes referred to as narrow level differential, float switches of this type can send a series of signals as the liquid level rises or falls. Liquid level switches are available for top or bottom mounting. Tank level switches mount on the side, while a leak-detecting switch does exactly what the name suggests.


It’s usually best not to empty a tank completely, as that can draw sediment. A tank level switch will send a signal before that happens, closing a valve or operating a pump. Overfilling is bad, too. It can compromise the quality of product being processed or stored, push the tank beyond design specifications, and even lead to catastrophic spills. Level switches play a role in every liquid handling and storage process. From water treatment and distribution to chemical manufacturing, power generation, and food and beverage production, every industry benefits from our reliable flow switches.


Level switches for tanks are “fit and forget” devices. Not easily inspected or serviced, the only indication of a fault is flood or drought. The resulting costs can be astronomical, even including lawsuits and fines. That’s why it’s essential your liquid level switches are made from the highest-quality components. An inexpensive level switch could be a costly mistake!


We source quality materials from reputable vendors. Our processes and people are certified, and we design for reliability. With Thomas Products LTD, you can trust the durability of every float and level switch we produce. Our level switch catalog describes the many standard tank level switches we offer. Click the link for details and please search our inventory. We also understand that demanding applications sometimes require a unique solution. That’s why we’ll design a custom level switch or custom float switch to suit your needs.

Custom Level Switch Product Selection

Please download and fill out the custom selection guide. Once filled in be sure to save the guide and email it to us at sales@thomasprod.com

Once we receive and review your selections we will contact you to complete your order.
Steps to submit the form:

  1. Click download link below
  2. If the PDF opens in your browser click the download/save icon
  3. Open the PDF with Adobe Acrobat
  4. Make selections and save the PDF
  5. Email the saved PDF to sales@thomasprod.com


Pump controls are found in any application where it is necessary to monitor and regulate aspects of pump operation and liquid flow — such as pressure and volume — through a pump. Pump controls can act as switches, turning flow or injection on or off, or can be used to govern and control flow rates on a constant basis. A high-quality pump control must be constructed from high-quality components because quality and reliability are vital to ensuring that the pump control operates as required.


The failure or malfunction of a pump control can cause numerous serious outcomes. These include:
• Injury to users of a pump or those near it
• Damage or destruction of other equipment, such as valves or pipes
• Damage to the surrounding area
For these reasons, it is essential to select a superior pump control that meets or exceeds the standards of your application.


Pump controls are found in any industry and application where liquid flow must be regulated or where liquid levels must be monitored. Uses include:
• Level pump control — These types of pump controls monitor the level of a liquid in a vessel and trigger a pump to start once a certain level is reached. A vast number of industries use these controls, including manufacturing, waste removal and HVAC.
• Pump control switch — A pump control switch is used to start or stop the function of a pump based on the liquid level. A standard application of this switch is to stop the pump once all liquid has been removed, so it isn’t damaged through dry operation. Pump control switches are found in applications such as wells and sewage infrastructure.
• Flow regulation — Pump controls also can be used to facilitate flow rate and direction in order to achieve laminar flow through a pipe or valve. This ensures greater accuracy and more reliable flow.


While pump controls are ubiquitous across nearly all industries, they aren’t all alike. Differences in quality, construction and customization can have a major impact on the operation of pump controls — and their supported components as well. Thomas Products LTD uses only the highest-quality materials to ensure reliability, and works closely with our customers to provide the solution they need, from standard to fully customized products. Search our inventory to find the pump control that’s right for your application.


The non-electric flow indicator from Thomas Products LTD offers several options for monitoring the flow rate of water or any other liquid. With several high-quality material choices available, this flow indicator switch is built to be durable, reliable and suitable for any liquid flow monitoring task you may require. Features and options of this liquid flow indicator include:
• A 5.0 GPM flow meter indicator and a 1.0 GPM flow meter indicator option
• A choice of stainless steel or brass housing, with full SST or brass construction based on your selection
• Availability of high temperature modifications
• Minimal pressure drop (less than 1 PSIG)
• The 5.0 GPM fluid flow indicator can be installed in any mounting orientation; the 1.5 GPM flow indicator must be installed horizontally
• Each flow rating is based on use as a water flow indicator — with higher viscosity liquids, the switch will trigger at lower flow rates.
Applications of this liquid flow indicator are broad, as it is suitable in any setting where liquid flow must be monitored with a binary visual indicator of the flow condition. Typical uses include:
• Medical pump flow indication, such as morphine pumps
• Flow indication for utility infrastructure, such as water
• Chlorine pump flow indication
• Chemical pump flow indication
• Irrigation and other agricultural uses
• Emergency water system flow indication


This non-electric liquid flow indicator offers versatility, quality and high performance, with only the best quality materials used. Additional benefits include:
• Versatile and customizable options based on your needs — choose from brass or SST housings and 5.0 or 1.5 GPM flow rate indicators
• Full construction of all wetted parts in your chosen material
• Reliable flow indication at a reasonable cost
• Easy installation, operation and state reading — the red or green indicator quickly shows whether the flow condition is being met
• For the 5.0 GPM indicator, the option for vertical or horizontal installation
• Negligible displacement and disruption to the flow rate
• The ability to operate with any liquid or water condition — clean, dirty, slurry, etc.
• A simple solution when more complex indications or readings are not required


At Thomas Products LTD, we specialize in providing an extensive range of controls, switches and indicators to satisfy all fluid monitoring needs across a wide range of industries. Our breadth of product selection combines with our depth of experience in the field to offer the best products, product combinations and systems to our customers. In addition to our deep inventory, we have extensive experience in fully customized solutions. These include flow indicators, flow switches, pump controls and more. Begin by browsing our inventory selection and options for the right product for your needs, and contact us with any questions or customization inquiries.


A tank level indicator quickly and easily shows whether or not a liquid remains at an acceptable level within a storage vessel, such as a tank. The tank level indicator will show one color of a switch — typically white or green — when the level is at or above the acceptable level. The indicator will display another color — usually red — if the liquid falls below that level. Our liquid level indicator products can be easily viewed, even at far distances, giving you an efficient and low-cost way to monitor liquid levels. With a water storage tank level indicator, you can remain assured that storage tanks are not leaking and contain the proper amount of liquid. These indicators are used to monitor levels in emergency water storage tanks, such as fire abatement, as well as tanks and vessels for industrial applications, utilities and more. Level indicators can also be used for other types of liquids, including hazardous materials and environments.


A non-electric water level indicator from Thomas Products Ltd. offers several benefits:
• Non-electric construction means easy installation and suitability for any scenario or environment.
• Water level indicators can be seen from up to 100 feet away.
• Simple color-based indication makes it easy to determine whether or not the liquid is at an acceptable level.
• Level indicators are suitable for many types of liquids, including viscous liquids and contaminated liquids.
• High-quality construction from top-rated materials means tank level indicators are durable and will always perform up to spec.
• Easy installation — no journeyman pipefitter required, and no need to install special bushings or fittings.
• Non-electric indicators can be put into operation very quickly, with minimal installation time and effort.
• Customizable to any level that you need monitored.
• Thomas Products Ltd. specializes in custom construction and is ready to work with you on any application or installation you may require.


Thomas Products Ltd. prides itself on being a different type of level indicator provider. Many suppliers you may encounter simply repackage and sell indicators made overseas — from lower-quality materials with fewer quality checks in place. However, we believe in American manufacturing and are dedicated to providing only the highest-quality indicator products. We choose quality materials — typically bronze and stainless steel — and, whenever possible, give you the option to customize your construction material. We have decades of experience in the level indicator field and offer unparalleled customization services tailored to your needs. View our extensive inventory of level indicators and flow monitors today, and contact us with any questions.

Flow and Level Switch Selection Guide

Shop For Products From The Premier Flow Sensor Manufacturer

Thomas Products LTD carries a wide range of flow switches, level switches, pump controls and non-electric indicators, as well as an array of pump control accessories in various sizes and configurations. In addition to our extensive inventory of stock products, we specialize in custom sensors, switches and controls, using only the highest-quality materials to ensure reliability and peak performance with your equipment. It is important, as a flow sensor manufacturer, to strive to meet the needs of customers. We are pleased to do so through our product and custom service offerings.

Our product focuses are:

Flow switches — Used to gauge and regulate the flow of liquid through a channel, flow switches actuate once a set point is reached, bringing the flow rate back to the acceptable parameter. An important component of the switch is the flow sensor. As a quality-focused flow sensor and flow sensor manufacturer, our switches are made of high-quality silicon and other superior materials.

Level switches — We are a level switch and level sensor manufacturer that delivers the most accurate, reliable equipment to our customers. Level switches sense and respond to the level or height of a liquid, and trigger an event such as turning on a pump or activating an alarm. As a custom level sensor company, we can manufacture level sensors to any specification you require.

Pump controls — Pump controls are used to activate a pump in response to a certain event, and are typically used in conjunction with flow switches, level switches or both. Our pump controls are designed for versatility and high performance, ensuring that liquid flow and levels are kept within acceptable specifications.

Non-electric indicators — Non-electric indicators are easy to install and can readily provide baseline level readings with a minimum of resource expenditure and investment.

Accessories — Our line of accessories includes an inventory of adaptors and other installation requirements for controls, switches, and sensors.

Industries Using Flow and Level and Sensors

Our products are used in a wide range of industries and applications, including any area where the level or flow of a liquid must be monitored and addressed. Some of these applications and industries include:

Chlorine pumps — Commercial and institutional pools require professional-grade chlorine management, and our equipment is up to the task.

Flood pumps — Automated activation of flood pumps, based on level and flow sensors and facilitated by pump controls, can be key to avoiding or mitigating disasters caused by high liquid levels.

Blood coolers and heaters — Environmental regulation of biological material is critical in the medical industry, and sensors, sensors, and switches automate the process of keeping stored blood and other material at an acceptable — and usable — temperature.

Morphine pump regulators — Automatic operation of devices like medicine pump regulators in ICUs and other medical settings is critical to the safety of patients and the ability of medical staff to work efficiently.

Working With Thomas Products LTD

We are a flow sensor company that delivers the most accurate and durable products available. Our extensive inventory and experience with customization allows us to meet the needs of any industry or application where flow and level sensors are used, as well as the necessary pump controls and accessories to complete your infrastructure. To discuss the benefits of our experience, and our commitment to high-quality materials, review our inventory and reach out to us today.


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