The Art of Practical and Precise Strain Based ... - Webprofile.info

Applications Note 1-12:Wet/Wet:Wet/wet differential pressure sensor designs are usually configured withthin flexible metal isolation diaphragms, ref Figure 1-48, used with anessentially incompressible silicone oil fill to communicate both P 1 and P 2to the spring member. Wet/wet differential pressure sensors are sometimesreferred to as Òhostile/hostileÓ designs and tend to be more costly thanother differential designs.Dry/Dry:Dry/Dry differential pressure sensor designs are the least expensive differentialdesigns available and will tolerate only dry nonconducting and noncorrosivefluid or gas exposure on either side of the sensor spring member.Often coatings are used to render these designs tolerant of short term exposureto moisture or condensate accounting for the popularity of this designfor heating, ventilating and air conditioning (HVAC) use.High Side:ÒHigh-side onlyÓ differential pressure sensors are designed such that one ofthe two pressure ports must always be maintained at a pressure that isgreater than the other port. Generally, the internal geometry of such designsis such that the spring member is well-supported for bending in one directionand poorly supported for bending in the other direction. In some cases,the sensor manufacturer will specify that the low side may be some smallpercentage of rated pressure greater than the high side. Generally, if a highside only design is subjected to full pressure reversals or the ports are confusedon installation, irreparable damage results.The Art of Practical and Precise Strain Based Measurement 2nd Edition © 1999 CHAPTER 1-79