Fluid Switch Blog

oil water mix

Oil & Water Might Not Mix but Here’s How to Measure Their Liquid Levels Anyway

Oil and water don’t mix. It’s not only a common analogy used to describe two things that are very different from one another, it’s also something that’s visually obvious if you’ve ever poured the two liquids into the same vessel. The oil will always float to the top because of density and the molecules in each substance. In other words, their specific gravity values are different.

When it comes to monitoring liquid levels in a tank this might seem like an issue but with the right level sensor, it’s no problem at all. Here’s why.

First, let’s look at a more practical scenario of this occurrence:

In a tank that collects runoff at a worksite, for example, both water and oil will be present. A pump is used to remove excess but must do so by taking each substance out one at a time.

Oil, since it floats to the top, can be removed first and then recycled. The level sensor should indicate when all the oil’s been removed and turn off before water is accidentally pumped into the new oil reserve.

SMD Fluid Switch fs20

SMD answers to the call for needs like this and more with its FS20-2090.

The FS20 model float switches are intended to be used as an oil/water interface switch that will sink in oil and float on water. Made from 316 stainless steel and custom-designed for high-pressure applications, the models have a specific gravity of .70 with 150°C max temperature and a max PSIG of 750.

If you’re in the market for a specific density sensor to work with your application, let the experts at SMD Fluid Switch help. We can provide full size, miniature, specialty and customized vertical float switches perfect for the job whatever your industry and whatever your needs.

Contact us today!


Perfecting Moisture Control with Liquid Level Sensors

For people living in New England this summer, humidity has become a regular weather occurrence. In addition to threats for tropical storms, the conditions make the skin feel sticky and even make it difficult to breathe.

To assist with keeping rooms at reasonable temperatures and conditions, dehumidifiers offer a solution. These machines work to remove moisture in the air and prevent mold, dust, and allergens as well as reduce energy consumption. To do so, they pull moisture into the dehumidifier and process it through coils that are cooled with a refrigerant. The result is cooler, drier air.

Recognizing how much moisture has been removed and when the machine should and should not be running requires accurate measure.

By adding a liquid level switch to your dehumidifier you can provide customers with a more reliable and efficient machine as well as more comfortable living conditions.

Other parts of the country are also battling record hot temps but they are experiencing the opposite and instead dry air wreaking havoc on comfort levels. Humidifiers can be used to add just the right amount of moisture back into the air. As A/Cs are in overdrive cooling spaces, these machines need to accurately release moisture levels in the air. With a level sensor placed inside the machine, you don’t have to worry about the humidifier running constantly or erroneously turning on once water has run out and causing breakage.

SMD Fluid Controls manufactures and supplies a wide variety of fluid switches, float switches, temperature gauges, and liquid level sensors. Looking for a standard off-the-shelf product or custom sensors designed to meet your specific needs? We can make sensors to measure anything!


liquid level sensors

Level Sensors: How They Work & What They Do

How do you measure the level of liquid in a contained space that’s flowing freely and in some cases too hot or dangerous to come in contact with? The answer is –  Level Sensors.

Using a magnet and reed, the most basic sensors can monitor liquid levels through the activation of switches that activate alarm about too much or too little liquid present in the container.

But don’t let their simplicity fool you. Level sensors aren’t just loved because of their cost sensibility, they are also vital to operations in industries across the globe. They don’t just measure the presence of a medium in a container, but also the absence. These low-level warnings and can even detect leaks before dangerous situations occur. This accuracy and dependability keeps businesses successful and the public safe.

Liquid measurement and monitoring is so important in fact, that new devices and technologies continue to incorporate the sensors in them as a way to deliver important data to and from advanced machines.

Depending on the type of process materials being measured, different sensor types can be used.

Two options for how to handle materials are typically chosen from – contact or non-contact measurement. This is based on various factors from the density to the temperature of the material being measured and whether or not there are sanitary requirements. As the name indicates, a contact measurement method would be the sensor located inside the vessel itself and able to come in contact with the material being measured without putting the project at risk. A non-contact method would include a sensor mounted to the outside of the tank.

Here is a break down on the different types of sensors offered by SMD Fluid Controls.

Contact Sensors:

Float Switches – These are the most commonly used devices for level measurement and utilize magnetic floats and reed relays to measure liquid medium.


FL50 – Chemical Resistant Plastic Ultrasonic Point Level Sensor


Contacting UltrasonicThese options are great for point level measurement of liquid and work by measuring the timing and speed of sound waves.

Optical SwitchesThese sensors have built-in electronics and work with no moving parts. They can perform point level sensing and pressure sensing up to 2500 psi.

optical sensor

OS950 – Miniature Plastic Optical Level Sensor

Submersible Tank Level Sensor – These are a versatile option that can gauge tank levels by the hydrostatic pressure and offer stable and continuous measurement from depths up to 211 meters.

submersible sensor

FT60 – Downhole Submersible Level Sensors

Non-Contact Sensors:

Ultrasonic Radar – This option uses radio waves to measure levels and is best for highly viscous or difficult liquid media that must be measured in real-time. Our ultrasonic sensors are made from 316 stainless steel and have a temperature maximum of 90°C with pressures up to 5,000 PSI in custom configurations.

Load CellsThis non-contact method of measurement is typically used outside of a tank to measure its contents by weight and may be suitable when non-contact with materials being measured is required.

Ready to order? Have questions?

Whether you need a prefabricated float switch or a custom designed liquid level sensor, we can help! Our full OEM services are available whatever your industry and whatever your needs! Contact us today!


Level Sensing in Healthcare: Improving Bioreactor Vessel Conditions

In the medical field, laboratories are filled with research and development teams testing and improving pharmaceutical drugs and other life-saving innovations. A key piece of equipment in this is a bioreactor vessel which is used to create a biologically active environment where chemical processes, as well as live organisms, can be tested and studied.

In order to work properly, the bioreactor vessel’s internal environment must remain at accurate temperatures, nutrient concentrations and maintain any pressurization or gases for fermentation or oxygen.

Level sensors incorporated into the bioreactor vessels helps manage these needs.

Level sensing is critical in medical environments and biotechnology especially inside a bioreactor vessel where the process of agitating broth, consisting of cell culture and raw materials, and allowing it to settle happens. Once the broth subsides, fermentation begins and this emits carbon dioxide as a result of cell growth.

The Problem

While the vessel consists of filters responsible for the gas exchange and protection from outside contaminants, a foaming resulting from fermentation creates a unique problem in the vessel. If the foam level reaches the filters, it then disrupts the gas exchange and can even damage the filter itself.  Once this occurs, staff must use a pricey de-foaming agent to lower the foaming level in the vessel so its use is economically unsound.

Capacitive Level Sensors

At FluidSwitch we can help with this issue by installing a capacitive level sensor, also known as RF admittance. This will only diffuse the de-foaming agent when the level sensor detects foam.

The Capacitive level sensor works by, “processing capacitance with reference to the dielectric constant of the material being measured and the voltage being used to complete the circuit. These measurements are used to determine vessel levels. Higher levels of dielectric material result in greater capacitance, meaning the former can be easily gauged with the latter.”

Utilizing this sensor would decrease the cost of the defoaming agent as well decrease the loss of expensive culture in the vessel due to damaged filters.

Spend less time trying to keep the bioreactor vessels contents safe and more time focused on developing new important innovations.

Get in touch with Fluid Switch today!

irrigation on farm

Better Irrigation Management with Ultrasonic Liquid Level Sensing

It’s no secret that today’s farmers and the agricultural industry as a whole are faced with many challenges when it comes to providing high quality and consistent food for consumption.

One of the largest risks is food waste and the discarding of less than perfect crop yields for selling in stores. These deformed fruits and vegetables and those with abrasions are adding up 20 billion pounds of produce that are being left out.

The USDA has found that “30 million acres of cropland, 4.2 trillion gallons of irrigation water, 1.8 billion pounds of nitrogen fertilizer, and 780 million pounds of pesticides went into producing food that was thrown away.”

Controlling the delivery of water to crops is important for sustaining profitable yields of food production and has been around for ages.

For this blog, we’ll look at a key way to turn things around and it starts crop-level with the resources being used to monitor and deliver vital water to these plants. Referred to as, “precision agriculture” farms can maintain precise water allocation as a tool for curbing food waste.

This is done through the use of ultrasonic liquid level sensors.

Today, automated irrigation distribution systems are becoming a popular choice over traditional methods because they remove the intensive human labor required to open and close gates and they provide much greater accuracy when it comes to water level measurement.

As an effective method, irrigation staff is no longer needed to manually raise gates to release water. Not only reducing intensive labor demands and saving water but also removing the factor of human error from the equation.

Utilizing ultrasonic liquid level sensing, sensor-driven channel gates that distribute precise volumes of water based on requested parameters are possible.

There’s more.

The sensors are also collecting important data that can be shared with farmers to provide exact details on how much water was delivered and help define future orders. Reducing waste of precious water resources especially during a drought, and even protecting crops from rot and damage due to overwater.

SMD Fluid Controls offers a variety of ultrasonic liquid level sensors and transmitters for continuous, non-contact tank level measurement. Our industrial ultrasonic sensors operate using the most state of the art working principles and are available in a variety of materials and prices.

Get in touch to learn more about how we can help with your application’s specific requirements.

heat wave sun

Surviving a Heatwave: Float Switches Make Generator Power Reliable

As a heatwave makes its way through many U.S. states and record temperatures are predicted, it’s important to remember the chances this weather has to also create dangerous conditions at work and at home. Everything from tropical storms, lightning, and power outages are possible.

In some cases, power outages can be truly detrimental. Consider the hospitals where lives depend on electricity to keep people alive or construction sites and factories where power is critical to maintaining operations and productivity.

The chances of an outage during extreme heatwaves are attributed to increased electricity consumption and high-temperatures as well as storm damage.

Luckily, generators exist to ensure power can be maintained at these critical sites. Even these, however, require fuel and ongoing maintenance to operate properly.

Enter float switches.

Keeping generators working reliably and without hiccups requires a steady supply of fuel. Float switches can monitor fuel levels to prevent overflow and to ensure the equipment never becomes low, leading to shut off.

In the case of either condition becoming an issue, the float switch can also be used to send an alarm and alert users of the changed conditions before it becomes a spill or breakage.

Whether you need a prefabricated float switch or a custom designed liquid level sensor, SMD Fluid Controls can help. Get in touch today!

Understanding which generator is necessary for your needs is important to guide you to the float switch application best suited to monitor and maintain that power source. Once you’ve selected the appropriate equipment, monitoring standards can be set.

SMD Fluid Controls offers a wide variety of industrial float switches and liquid level sensors as well as custom multilevel fluid switches, combination level and temperature sensors, ultrasonic liquid level sensors, and optical level sensors for a diverse range of uses.


What Makes a Float Switch So Accurate?

Float switches are central to what we offer here at SMD Fluid Controls. The devices in a basic explanation include a hollow float, magnet, reed contact, guide tube and retaining collars. Depending on the position of the magnet, when the device is in use it will either pull the reeds apart or force them together. When the reed contacts are forced together it closes a circuit. (See this app note for more details)

Determining Liquid Levels

Float switches are used commonly to determine the level of liquid present, or absent, in a vessel. The sensors are low cost, very reliable and accurate and depending on the material they are constructed of, can be used in a variety of different liquid media.

Interested in purchasing float switches to meet your project needs? We everything from liquid level sensors, float switches, sump switches, optical sensors and more. We also work with you on custom design and manufacturing.

Going Beyond Liquid Measurement

In addition to measuring liquids, a float switch can control a pump, activate an alarm and even be used to control another electrical device.

One example of the way a float switch can work is sump pumps. Anyone unfortunate enough to deal with flooding issues in a home or business know that these machines are important to keep water out the space. But you can’t sit by waiting for the water level to accumulate so you can turn the device on. Instead, a float switch is used to monitor rising water levels and then activates the pump (switches it on) when a threshold is met. Once the level is no longer determined by the switch, the pump will turn off again and continue monitoring for the next occurrence.

Discussing Accuracy

So what makes float switches a tool that’s stood the test of time? Flexibility and reliability. Engineers opt for the devices not only because they can be mounted in different ways and made of materials for use in different environments, but also because they are durable and can do the intended job for a great number of cycles with little need for maintenance.

Contact SMD today!

oil fried chicken at resturant

Level Sensor & Float Switch Applications: Restaurant Oil & Grease

Restaurant owners have a number of responsibilities to ensure safe conditions are maintained for both workers and patrons. In addition to food preparations, there is also the need for proper, sanitary disposal of foods and cooking greases that must be handled.

The process for recycling and removing grease and waste oil has evolved over the years. In the past, the draining and removal of gallons upon gallons of oil happened by the bucket and bin full. Most restaurant owners would pay for the delivery of new oil and removal of waste.

Today however, with the increase in biofuel vehicles and rising gas prices, waste oil has found more importance than before. In fact it has become a commonly stolen item from the back of restaurants and owners have been looking for ways to handle waste oil more efficiently.

Enter level sensors and float switches which find application in the tanks and storage bins. They help make the process of retrieving and disposing of waste oil a smoother and more effective one for restaurants.

SMD Fluid Switch is your source for any custom design and OEM services to help your restaurant meet better waste oil removal and recycling goals. To learn more about what SMD Fluid Controls can do for you, get in touch today or keep reading.

Modern fryers offer the safest option for grease and oil removal because they can be directly hooked up to a pump system that removes hot, old grease from a fryer without any interaction or handling by a human worker. This reduces accidents and helps kitchens to run smoothly.

SMD Fluid Controls offers vertical float switches and horizontal float switches in a variety of sizes and materials.  A level sensor can alert restaurant staff when a storage tank is full and needs to be changed or picked up by the oil recycling company and can prevent overflow.

In manual oil waste removal process systems, temperature sensors can also be added so workers responsible for the removal know that temperatures are safe for moving the liquid out. SMD Fluid Controls’ temperature sensors work with extreme precision by gauging electrical resistance relative to the temperature of the surrounding fluids.


The FM22 – Combo Level/Temperature Switches are a terrific option for this application. These switches work well in oils and with the bimetal snap-action temperature switch, can be used to shut down a fryer if the oil goes over temperature to help protect heaters.

Have an idea or need help with the waste oil system at your restaurant? We’d love to help!

SMD Fluid Controls designs, manufactures, and sells float switches and liquid level sensors of all types, for a variety of industrial applications.  Get in touch today!


Demand for Automotive Level Sensors Rises

Driving an automobile is a pretty simple function for most drivers licensed to be behind the wheel. As long as a vehicle is well maintained, all that’s needed is a simple turn of the key to be on the way. But what happens under the hood is a system of connected parts and technologies that are making the smooth ride possible.

Automotive components continue to advance and make our cars safer, smarter and more efficient. For manufacturers, it also leaves room for growth and innovation.

New research from ReportsnReports shows that level sensors, which are used to detect fluid levels and signal changes, continue to play an important role in automobile mechanics. In fact, a look at the level sensor market for 2022 shows growth at 4.13 percent.

SMD Fluid Controls offers level sensors and float switches to meet any of your upcoming project or product line needs.

Get in touch to learn more!

From measuring the fluid in your braking system as well as important water cooling to stop potential dangers, to keeping your washer fluid reservoir full – there are so many ways level sensors and float switches can be used in automobile applications.

An ultrasonic liquid level sensor is one option that can be used to measure diesel exhaust fluids and help reduce emissions. In other practical uses, a level sensor can eliminate the need to constantly check that fluid levels are filled. Instead with onboard electronics and attached to reservoirs filled with important liquids such as coolants and breaking fluids, lights on the driver dashboard can confirm proper operation or prevent unnecessary breakdown with an early warning.

The research report also attributed the rise in the market to the fact that consumers are interested in these advanced displays on their instrument panels which provide more information about what’s happening under the hood of their car.

Have a product you’re developing and need help completing the design? Contact SMD Fluid Switch and speak with one of our engineers. Our expertise in custom design, manufacturing, and more for a variety of applications and industries, means we’ll have a solution to complete your idea, no matter how unique.


Liquid Level Sensors & A/C: Tips to Beat Summer Cooling Expenses

Summer heat is one of the hardest conditions to endure. Both from the standpoint of humidity and uncomfortable working conditions to being unable to feel comfortable in ones living space. Then there’s also the added dangers of spoilage and machine breakdown caused by extreme temps.

As a result, it’s important that A/C and other cooling equipment are used to maintain appropriate temperatures at these locations. Achieving this is dependent on the conditions and area needing to be cooled and will require  A/C systems that continually work hard.

The A/C is able to a cool space through the use of chemicals like refrigerant (Freon) by converting gas to liquid and back again.

Maintaining these systems in commercial and residential settings is important. Breakdown poses a cost risk in addition to adverse health risks from the heat. Ensuring that the compressor, the condenser, and the evaporator are all working properly is important.

Not to mention, Freon is expensive. Wasting large amounts can result in hefty cooling costs. To ensure its staying put, a method to measure the presence or absence of the liquid is important.

Enter the liquid level sensor.

As a manufacturer and supplier of a wide variety of fluid switches, float switches, temperature gauges, and liquid level sensors, SMD Fluid Controls can provide standard off-the-shelf products and custom sensors designed to meet your A/C systems and equipment builds.

Level Sensors in Cooling Systems

Designing innovative cooling units requires advanced technologies. A level sensor makes it possible to measure liquid levels and prevent premature breakdown and loss of comfort for consumers.

From low level switches that warn of coolant running out, to Freon recovery switches that ensure each drop is used efficiently, the possibilities are endless for creating effective cooling solutions. This has become more so the case today especially as lighter, more advanced equipment is being introduced.

A float switch can also be used in condensate overflow pans to prevent leaks and overfills from happening or even trigger a shut-off in applications where drains become restricted.

Reduce maintenance requirements while saving on rising Freon costs – find the float switch right for your application with the help of SMD.

 We work to lower costs and increase productivity. Contact us today to get started.