Hygrostat

Description of the Hygrostat
The Polyga® humidity measuring element consists of several synthetic fabric bands, each with 90 individual fibers of 3μm diameter. A special process gives the fibers hygroscopic properties, allowing the measuring element to absorb and desorb humidity. The swelling effect, mainly in the longitudinal direction, is transferred via a lever system to a microswitch with an extremely short switching path. The measuring element reacts quickly and precisely to changes in air humidity. By adjusting the setpoint value control knob, the lever system is engaged so that when the set air humidity is reached, the microswitch is activated. The fan-shaped measuring element is housed inside the enclosure and must be protected against coarse dust, dirt, and water. The sensors are designed for pressureless systems. The mounting position should be chosen so that condensed water cannot enter the interior of the housing. Any mounting position is possible, preferably with ventilation slots across the direction of wind.

Application
The HG hygrostat is used as an on-off controller to regulate relative air humidity. It can be used to control air humidifiers and dehumidifiers in offices and computer rooms. Other areas of use include food and luxury food storage, cooling rooms for fruit and vegetables, greenhouses, the textile industry, the paper and printing industry, the film industry, and hospitals. The hygrostat can be used almost anywhere that air humidity needs to be regulated or monitored. The HG Mini-i room hygrostat is designed so that the adjusting knob and scale are inside the housing, making unauthorized manipulation by third parties more difficult. The HG Mini Schnapp version is additionally equipped with an adapter for DIN rail installation.

Technical Data:
- Scale range	30...100 % rh
- Measuring accuracy	±3%
- Range of operation	35...100% rh
- Switching difference (microswitch) ref. to 50% rh	approx. 4% rh
- Max voltage	250 VAC

If the relative humidity Fx (actual value) falls below the setpoint value Fw, contact 1/4 opens and contact 1/2 closes.

Mounting
The hygrostat must not come into direct contact with water, e.g., splashed water when cleaning the climatic chamber, etc. The mounting location should be chosen so that a representative measurement of the air humidity can be guaranteed, i.e., the humidity readings at the mounting location should correspond to those in the room. The hygrostat should be exposed to the flow of air.

Maintenance
The measuring element is maintenance-free in pure ambient air. Aggressive media containing solvents can cause measuring errors and failure, depending on the type and concentration. As with almost all humidity measuring elements, deposits which eventually form a water-repellent film over the measuring element are harmful (such as resin aerosols, lacquer aerosols, smoke deposits, etc.).

It is extremely important that the temperature remains constant during measurements of relative air humidity. The air must be homogeneous.