Float level switch
Level switches with REED technology without power consumption. Level switches are used for point level indication in liquids, control of e.g. pumps and valves via intermediate relay. The level switches work with both electrically conductive and non-conductive liquids.
SUBVAKT
Level sensors with new crimping technology and tight cable fastening, as well as good strain relief. Float switch made of stainless steel, SUS-316, that can be submerged up to 30 meters.
Level switch in Brass
Level switches with brass tubes and BUNA-N floats. The level switches are suitable for petroleum products or other non-aggressive liquids.
Level switch in stainless steel
Level switches with pipes and floats in acid-resistant steel SUS316. The level switches are suitable for water-based liquids and can be used in harsh/aggressive environments.
Mini float level switches
Small level switches for narrow spaces. The level switches are available in materials such as PP, acid-resistant, and brass.
Marine approval level switches
Level switches with one or two levels. The level switches can also be obtained with overtemperature protection.
Our production of level switches
We also manufacture custom level switches. These are built according to the customer's requirements and with a unique customer-specific drawing number.
Made in Sweden
HEMOMATIK - sensors since 1973
Our production of level switches primarily takes place in Östhammar. Initially, the level switches were mainly manufactured for electronic overfill protection for oil tanks. The range of level switches was expanded in collaboration with our customers, resulting in a variety of customized designs. The level switches are manufactured according to customer specifications and with a unique drawing number. At the same time, a standard range of level switches and combined switches for both level and temperature was developed.
How does a level switch work?
Connection and function
The level switches contain one or more REED switches that are embedded in a tube made of metal or plastic. A REED switch - also called a reed element - is a gas-filled glass tube with two contact reeds that overlap but are separated by a small air gap. When a magnet approaches, the contact reeds quickly close so that an electrical circuit is formed.
Strong vibrations and impacts against the level switch can damage or affect the REED switch. Therefore, handle the level switch with care.
Level function
A float with an embedded magnet follows the liquid surface along the non-magnetic sensor tube, which contains 1 to 5 REED switches. The magnet activates each reed switch over approximately 10 mm, a so-called passing contact function.
To obtain a latching signal instead of a passing one, a stop ring is used above or below the float. This prevents the float from moving outside the allowed range.
Contact function is indicated when the tank is empty and the sensor is mounted from above.
Designations
O = open circuit at low level, closes at rising level
S = closed circuit at low level, opens at rising level
V = alternating contact function (S and O)
X = S- or O-function via reversible float.
SP = closed passing function
OQ = O-function with splash guard
SQ = S-function with splash guard
Reed switch
A reed switch has a long mechanical lifespan. The lifespan is dependent on the load, which is why arc suppression may be necessary. The following solutions are commonly used:
Capacitive load
When connecting a capacitive load (including cables over 10 meters), a current surge occurs. The solution is a series resistor near the circuit breaker. Here we provide a simplified formula for calculating the resistance value.
Of course, there is always an advantage to having a higher resistance, but voltage drop and power must be taken into account. (Image 1)
Inductive load
In case of direct current, a arc suppression diode across the coil is the best solution, sometimes in combination with a series resistor (for cables over 10 meters). For alternating current, an RC protection is chosen. (Image 3, 4)
REED technology and energy
Hemomatik has over 50 years of experience in manufacturing level switches and temperature switches.
One of our specialties is level switches with floats and REED technology. The level sensors have no power consumption of their own and provide great advantages in applications such as battery-powered devices, wake-up sensors, and IoT. Additionally, any number of level switches can be connected in series or in prallel.
Since the REED switch is a passive component that only breaks or closes the circuit, the user has full control over their energy consumption by allowing very small currents to pass through the level sensor. This also provides a very long durability.
The REED switchdoes not require power to close or break since it is the float's magnet that causes the contact to change position.
The REED contacts are very small and weigh only a few grams. Therefore, they require minimal resources during manufacturing. They consist of a small glass tube with metal tongues inside and can be easily recycled. Of course, they comply with RoHS and REACH, so they do not contain any lead or mercury. All of this results in significant energy savings and reductions in carbon dioxide emissions.
Hemomatik constantly works to reduce the use of chemicals and chooses materials and construction methods so that our products are as environmentally friendly and as recyclable as possible.
Hemomatik is third-party certified according to ISO14001:2015 and ISO9001:2015.