Cleaning Sensor Elements Procedure. Permalert PAL-AT AT40K, PAL-AT AT50C, PAL-AT AT80K, PAL-AT AT20C, PAL-AT AT20K

8 Probes solvents. The probe is reusable by cleaning or replacing the sensor elements. There are 2 models of the PHLR probe available:

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The standard PHLR is designed for non-pressurized locations such as sumps, manholes, and nonpressurized containments. The PHLR can be installed in any orientation – vertical or horizontal.

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The PHLR-P is designed for pressurized containment applications. This model is ideal for typical sealed, containment piping systems which are maintained under pressure with a nitrogen or air blanket. The PHLR-P should be installed in a vertical orientation. The PHLR-P has vent holes that must not be submerged in a liquid before the containment is pressurized (see Figure 22).

An extensi on to the probe housing can easily be added with standard ¾” Schedule 40 PVC pipe to accommodate installation requirements.

Figure 21

PHLR Sensor Package

8.4.1 Cleaning Sensor Elements Procedure

The replacement sensor package consists of 8 disks: 5 screen disks and 3 sensor disks as shown in

Figure 21. The replacement package includes all removable parts: probe cap, sensor elements, and actuator. Replacement sensor elements only can also be purchased.

The following procedure is a general guideline to follow to clean the probe and sensor elements after exposure to hydrocarbon liquids. Caution: It is the user’s responsibility to determine safety precautions and the suitability of exposing personnel to the hydrocarbon liquid on the probes and various cleaning solvents suggested.

The sensor disks swell after exposure to fuels and solvents. The swelling forces the actuator to move and operate a low-force sealed switch. Volatile hydrocarbon liquids, such as gasoline, will eventually evaporate after a period of time resulting in the sensor disks returning to their original size. This allows the switch to return to the normal position. A faster resetting process is to disassemble the probe to speed the evaporation of the liquid. Other liquids such as diesel fuel and jet fuel, which do not evaporate, must be flushed with a solvent to remove the contamination. Disassemble and clean the probe as follows:

1. Remove excess hydrocarbon contamination from the exterior of the probe.

2. Hold the switch in a vertical position with the cap downward and unscrew the cap. It is suggested to do this over a table so the small parts are not lost if they are dropped.

Be very careful not to lose the sensor disks.

They are very similar to contact lenses in size and texture.

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