Monroe Electronics Electrostatic Fieldmeter - Static Monitor - model 177A - Manual (Page 15)

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Constant purging of the Model 1036 probe with clean dry air or an inert gas is recommended
whenever practical to prevent airborne contaminants from entering the aperture in the gradient cap
and being deposited on the electrode.
The air supply should meet standard ANSI/ISA-S7.0.01-1996 - Quality Standard for Instrument Air.
A Koby "Junior" filter available from Koby, Inc., 297 Lincoln Street, Marlboro, MA 01752 should meet
this standard and will provide sufficient mechanical and chemical filtration for one to four probes
under most conditions.
A complete probe purge kit, Model 1017/22G, is available for Model 1036F from Monroe Electronics.
It includes a low volume, long-life air pump, mechanical and chemical filters, and a supply of tubing.
The pump is fully capable of 24-hour per day operation, thus keeping the probe ready for immediate
use. A purge gas inlet tube supplied with each 1036F probe may be installed in either of two
positions, the choice of which is primarily a matter of convenience in routing of the hose carrying the
purge gas. These consist of tapped holes that exit at 90° to each other near the probe cable. If it is
desired to move the purge tube to the other location, simply switch it with the Allen set screw
plugging the other hole.
Purge the Model 1036E probe through a ¼"-18 NPT tapped hole in the end of the housing near the
cable exit using common plumbing or tubing components.
Gas pressure to either probe type should be sufficient to produce a slight positive flow out of the
probe and in no event should exceed a pressure of ½ psi.
Servicing
General:
It must be emphasized that the critical elements of these probes (gradient cap and sensing
electrode) must be kept free from contaminants, e.g., dust, fumes, mists or any foreign material. The
materials of which these probe elements are made were very carefully chosen to minimize contact
potential. Any foreign matter which will cause relative electrical activity when combined with relative
motion will tend to cause drift and measurement errors.
Therefore, it is recommended that:
 Probes be constantly purged even when not in use, if this is practical.
 Probes be kept tightly covered when not in use and are not being purged to prevent
contamination. A covering such as a plastic bag or aluminum foil may be used. DO NOT
cover the sensitive aperture with adhesive tape.
 Probes be cleaned only to the degree and frequency necessary to achieve the required
stability.
 Gradient caps NOT be removed for cleaning unless absolutely essential.
 Major cleaning and reconditioning be should performed by the factory.
Cleaning:
The recommended cleaning solvent is instrument grade 70-100% isopropyl alcohol applied with a
suitable soft, lint-free applicator. Use of a non-approved solvent may degrade performance
permanently, requiring factory service.
Outside surfaces of the probe should first be wiped clean with a lint-free wiping tissue saturated in
solvent. Then the interior surfaces should be flushed with solvent, using a plastic squeeze bottle
through the aperture until no dirt or dust may be seen. The probe should then be allowed to drain
and dry thoroughly. A 15-minute bake-out at 75°C is recommended to remove residual solvent.
Disassembly/Assembly, Model 1036E:
In order to rewire the cable terminal block, replace or standardize the probe assembly and, in most
cases, to calibrate Model 1036E, it must first be removed from its housing. This is done by loosening
the four cross point screws around the outer edge of the cover 1-1½ turns each, in turn, several
times while lifting the cover and probe straight out of the housing until it is completely removed. DO
NOT attempt to remove the screws completely one at a time. These four screws have circular