Pressure switches (Pressostats)
Pressure switches from Trafag are characterized by their compact design and high-precision micro-mechanics, wholly developed and manufactured by Trafag itself. They can be installed in any position without the need for electric power, making them particularly versatile in application, and fully site-independent.
A distinction is made between three separate measurement principles:
Piston
Pressure is transferred via a piston. The complete piston system is made of stainless steel, and therefore particularly able to withstand corrosion by sample media. The advantage of the piston system lies in its ability to cover large pressure ranges (1 to 600 bar). In addition it is non-sensitive to high pressure peaks or abrupt changes in pressure and is also able to endure a very large number of switching cycles. The piston system displays a relatively high hysteresis which increases with pressure. Due to the dynamic O-ring seal configuration, the piston principle is subject to a minimum of leakage problems. This type of sensor is safe at negative pressures. Ideal for hydraulic applications, at high vibrations, and for long serviceable life.
» Download piston data sheet H72267Bellows
Pressure is measured by means of a frictionless, sensitive bellows system. This enables highly accurate switching at low pressures (-0.6 to 40 bar). The hysteresis is accordingly small and, in the main, remains constant across the complete pressure range. Apart from in liquid media, measurement of vapor or gaseous media can also be made. The materials used are either stainless steel or a combination of bronze and brass, which can also be supplied nickel-plated. The permissible frequency of switchings is by comparison lower than for that for the piston system. This type of sensor is safe at negative pressures. Ideal for finely balanced pressure control.
» Download bellows data sheet H72271Membrane
Membrane sensors can also be used in liquid, vapor or gaseous media. Trafag distinguishes between two basic types of membrane.:
The membrane for the PICO family of pressure sensors combines the advantages of the piston type (ability to withstand high level of switchings, long operable life, resistant to pressure spikes) with those of the bellows system (narrower setting of switching intervals). The diaphragm is made of elastomer (FKM). There is choice of either stainless steel or brass material for the sensor housing. The switching interval increases at higher pressure ranges.
The membrane for the well-established pressure switches of the Pressostat range is particularly suitable for very fine pressure-control applications. The pressure range lies between 20...1000 mbar. The Housing is made of anodized aluminum, and the switching intervals remain to a large degree constant across the whole pressure range. This type of sensor is safe at negative pressures.
» Download membrane data sheet H72274
Optimal product selection
So that you can select the product best suited to your needs, you should know the following parameters of your application:
- pressure range
- max. likely pressure peaks
- sample medium
- number of switchings
- hysteresis requirement
- required accuracy
- media temperature
Further information
» Products pressure switches» Applications
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»Download Terminology of pressure instruments H72243
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