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in_m22.doc
Installation
Do not unnecessarily remove the dust filter from the HygroClip probe. The sensors can easily
be damaged when not protected.
General recommendations
Relative humidity is extremely dependent on temperature. Proper measurement of relative humidity
requires that the probe and its sensors be at exactly the temperature of the environment to be
measured. Because of this, the location where you choose to install the probe can have a significant
effect on the performance of the instrument. The following guidelines should guarantee good
instrument performance:
a)
Select a representative location
: install the probe where humidity, temperature and pressure
conditions are representative of the environment to be measured.
b)
Provide good air movement at the probe
: air velocity of at least 200 ft/ minute (1 meter/second)
facilitates adaptation of the probe to changing temperature.
c)
Avoid the following:
(1)
Close proximity of the probe to a heating element, a cooling coil, a cold or
hot wall, direct exposure to sun rays, etc. (2) Close proximity of the probe to a steam injector,
humidifier, direct exposure to precipitation, etc. (3) Unstable pressure conditions resulting from
excessive air turbulence.
d)
Immerse as much of the probe as possible in the environment to be measured.
e)
Prevent the accumulation of condensation water at the level of the sensor leads
. Install the
probe so that the probe tip is looking downward. If this is not possible, install the probe horizontally.
Installation and wiring of the base plate
The base plate should be installed first, using screws with an approximate diameter of 5/32".
Installation Note
(through wall installation and remote probes)
You may want to provide an orifice at a distance of about 3” from the probe of
the transmitter for future use by a reference probe and HygroPalm indicator.
The base plate of the standard M22 series transmitter is supplied with one
sealing cable grip. This cable grip provides effective sealing only with cables
having the proper outside diameter. Preferably, use a cable with an outside
diameter of 0.236 to 0.275 inch (6 to 7 mm) and with 18 AWG wires. Avoid
running the cables connecting the unit in the same conduit as 110 VAC power
cables. Depending on the installation, you may have to use a cable with
twisted pairs or a shielded cable to avoid electromagnetic interference.
In order to determine the maximum length of cable that can be used to connect the transmitter to other
devices, the first step is to find out what is the resistance per unit of length of the cable that you plan
on using. The maximum permissible cable length, connecting the unit to other devices, is determined
