PV-Seal FEEDTHRUs consist of five separate pieces (four pieces for 300 series FEEDTHRUs with a single hole). The pieces are the FEEDTHRU body, the cap, the upper follower, the lower follower (not in 300 series), and the silicone rubber sealant. The FEEDTHRU may also have unused holes blocked with removable hole plugs.
While holding the FEEDTHRU body, unscrew the cap by turning in the counterclockwise direction until it is free of the body. The upper follower is now visible in the top of the body. Note the number of holes in the follower and the fact that a protruding pin fills one of the holes. This pin is a "key" pin and is part of the lower follower. Do not attempt to remove this pin. Push a soft non-marring object into the bottom of the FEEDTHRU body to expel the upper and lower followers and the silicone sealant as a unit. If hole plugs were ordered with your unit they can be removed by grasping each one with a pair of pliers and pulling them out of the unit one at a time. Hold the lower follower in one hand and pull the upper follower off of the unit. The "key" pin is now clearly visible. Gently pull the silicone sealant off of the "key" pin. Disassembly is now complete. Do not attempt to remove the "key" pin from the lower follower.
Reverse the disassembly procedure. Note that the two ends of the silicone sealant are different. Place the sealant over the "key" pin so that the beveled end of the sealant matches the depression in the lower follower. Place the upper follower on top of the sealant with the long narrow end facing the sealant. If the thermocouples have thermocouple plugs attached, the thermocouple must be inserted through the cap before being placed through the follower/sealant unit. Failure to do so will force you to remove the thermocouple plugs to install the cap. Thermocouples should be inserted at this time. If unused holes remain, hole plugs must be used to fill them. Insert them at this time noting that the oval cross section of the plug should line up with the cross section of the sealant hole. Place this unit in to the FEEDTHRU body and screw on the cap until it is only finger-tight. Next, grip the cap between the thumb and forefinger and tighten the cap an additional one-quarter turn. At this point, assembly is complete.
The shape and material of construction of the sealant are designed to meet the special needs of the food and pharmaceutical industry. These needs require that the sealant seal gas and vacuum tight, retain resiliency, and have excellent memory of original sealant shape. The sealant can be used in the temperature and pressure extremes found in freeze dryers and steam sterilizers. The unique shape of the sealant holes allows for vacuum and pressure tight seals around the oval-like shape of thermocouples commonly used in the pharmaceutical and food industries. Tests have shown that the sealants are effective at vacuums of one micron and pressures of 200 pounds per square inch absolute with only light tightening forces on the packing gland. Easy removal and replacement of damaged thermocouples is accomplished once gland tightening force is released. Because of the excellent release properties and shape memory of the elastomer, long thermocouples are quickly and easily stripped from the gland.
The following directions must be observed to insure that the sealant will have a long and trouble free life:
• All unused holes must be filled with hole plugs.
• The tightening torque on the packing gland tightening nut must be carefully set and never exceeded. The appropriate method is to tighten the gland finger tight plus one quarter turn without use of tools and then subject the sealant to the pressure and vacuum levels in your process. If necessary, tighten the nut with an ordinary open end wrench until the required seal is achieved under both the maximum pressure and vacuum conditions of your process (but in no case more than one half turn). Because this method is only approximate, the seal should be periodically tested for leaks and tightened as necessary.
All OSHA regulations and laws must be adhered to with special attention to monitoring workplace concentrations of toxic gases, such as ethylene oxide, chlorine dioxide, and hydrogen peroxide. Because pressure vessel penetrations and seals are prone to leaks, they must be continuously monitored during use to allow leaks to be detected as quickly as possible.