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short-circuit of signal output leads, and short duration power line 

 transients up to 150 volts. Each is supplied with independent remote 

 zero adjustment, although this feature is not used in the present DPG 

 model . 



The fifth pressure-sensing diaphragm in the fuselage supplies 

 a signal measured by an absolute pressure transducer also located 

 inside the cylinder. The absolute gauge is a Setra Systems Model 

 205-2 of 50 psia range. It also operates on 28 volt DC nominal 

 excitation for a to 5 volt positive output. 



A. The Isolation Sensor Diaphragms 



The stainless steel diaphragms of the transducers are 

 protected from the harsh marine environment by the nine "isolation" 

 diaphragms located within the fuselage and arms, (Figure III-4) . The 

 isolation diaphragms are made of 13 mil DuPont Fairprene elastomer 

 mounted on an acrylic housing. Fairprene^ is a durable nylon 

 material, coated with neoprene, that is flexible perpendicular to the 

 plane of the fabric. The elastomer is sealed to its acrylic housing 

 by a 90-10 copper-nickel alloy ring. The 90-10 alloy was picked for 

 its anti-fouling properties. Bio-fouling across the diaphragm ring 

 could puncture the elastomer or restrict its ability to deflect and 

 thereby introduce a bias. The rings are designed to last at least 

 five years assuming a corrosion rate of 1.0 mpy, (Dexter , 1979) . The 

 ring is secured to the diaphragm housing with six Monel 1/4 inch 



