Paroscientific, Inc.

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Low battery indicationsDo not rely on the data displayed or transmitted when either of theselow battery signals is present. Replace the batteries in the Model 730or 740 or use the AC adapter. The Model 760 battery may berecharged by connecting the 760 to AC power.Please refer to the Specification Control Drawing (SCD)accompanying each unit for special features and options.Remote DisplayThe Model 715 is a 2-line, 16-character backlit alphanumeric displaythat is compatible with all Digiquartz® transducers that have dual RS-232 and RS-485 serial interfaces. It displays pressure withengineering units, and can optionally display alphanumeric text,internal transmitter temperature, or pressure as a percentage of fullscaleby means of a horizontal bar graph. Digiquartz® transducerscommunicate with the Model 715 via either RS-232 or RS-485.Depth SensorsMost <strong>Paroscientific</strong> Digiquartz® transducers are available in asubmersible depth sensor configuration.During installation, it is very important to have a bubble-freeinterface between the depth sensor pressure port and the outsidewater pressure. The pressure ports of <strong>Paroscientific</strong> depth sensorsare vacuum oil filled with Dow Corning FS 1265 silicone fluid. Thisfluid has a specific gravity of 1.25 and a viscosity of 300 centistokesat 25° C. The oil in the pressure port should be visible beforedeploying.Depth Sensors and Deep Ocean InstallationsThe Series 8CDP depth sensors are packaged in a machined PVC oracetal pressure enclosure and are available for depths to 700 meters.Output communications options are frequency signals or RS-232/RS-485 serial ASCII interfaces The Series 8CB depth sensors arepackaged in a machined 316L stainless steel enclosure, and modelsare available for depths to 7000 meters.Refer to the Specification Control Drawing (SCD) supplied with theunit for appropriate electrical and mechanical connections.6
Depth Measurement ConsiderationsThe conversion of pressure to depth depends on:1. The local value of gravity.2. The atmospheric pressure at the surface.3. The average fluid density between the pressure transducer andthe surface.4. The compressibility of the fluid. (significant at depths greaterthan 50 m)The local value of gravity, g local , varies by 0.5% over the face of theearth. This value depends primarily on latitude and altitude. Thereare also smaller corrections for local anomalies. Gravity can bemeasured at a site with a geodetic survey. If accuracy of 0.02% isadequate, local gravity can be determined from the followingequation:g local = 978.0309 + 5.18552 sin 2 Φ -0.0057 sin 2 (2Φ) -0.00009406 hwhere Φ is latitude and h is the altitude in feet.(ref. K.R. Lang Astrophysical Formulae 1980)Example: at Φ = 55 degrees and altitude h=2000 feet, the calculationgives g local = 981.317.Fluid density must be accurately known to obtain accurate depths.Fresh water density depends on temperature and varies byapproximately 0.5% between 0 and 30 degrees C. Typical values arebetween 0.995 and 1.000 gm/cm 3 .Salt water density depends on both temperature and salinity. Thesevalues generally change significantly with depth. Typical oceanvalues at depths less than 500 meters are between 1.02 and 1.03gm/cm 3 , but lower values may be found in coastal regions wheninfluenced by river outflow. In addition, water compresses at greatdepth so that a further correction must be made. A typical nearsurfacevalue is approximately 1.028 gm/cm 3. Never use anapproximate density value of 1.0 when computing depth in salt water.The result will be in error by nearly 3%.If the calculations of depth from pressure are done carefully, depthbelow the sea surface can be determined with an accuracy of betterthan 0.01%. However, the sea surface moves up and down with timebecause of tides, and this must be allowed for in referencing to asurvey datum. Conversion factors for density=1.000 gm/cm 3 andg=980.665 are tabulated as follows:7
Page 1 and 2: Paroscientific, Inc.Digiquartz ® P
Page 3 and 4: Digiquartz® Installation GuideThan
Page 5 and 6: TransducerBuffer tubeThe coiled buf
Page 7: Intelligent TransmittersSeries 1000
Page 11 and 12: Depth is determined by multiplying
Page 14: To obtain →multiplynumberof ↓ b

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