Houston Digital Instruments, Inc. ● 7240 BRITTMOORE RD ● Houston, TX 77092 Ph 713-688-8555 Fx 713-688-2228
Revision: 3
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installed an “orifice plate” to help minimize direct contact; in doing so, regular cleaning
should be performed to increase longevity with the above precautions.
SECTION IV
Theory of Operation
:
4.A
Pressure System:
The major components of this system are the transducer and the communications link (cable).
The transducer utilizes a four active arm Wheatstone Bridge Strain Gauge which, when
excited by the current source, will produce an electrical signal that is proportional to pressure
applied to it. The cabling serves as an interconnect for the transducer, taking the excitation
power in and carrying away the signal.
4.B
Factory Preset Calibration:
The HDI 2021 is a digital electronic pressure measurement device designed specifically for
Oilfield applications.
This system has been factory preset and will not require periodic
calibration as with the previous version of the HDI 2021 or to our similar product line, HDI
2400 Pressure Gauge Systems.
The HDI 2000 is based on a "Strain Gauge" design concept. The calibration of the strain
gauge is similar to tuning a stringed instrument. It is necessary to understand the system is
based on small resonant electronic signals.
The baseline for calibration is the current excitation across the bridge. This is preset at the
factory and cant be changed.
SECTION V
Maintenance:
5.A
Guidelines:
First, maintain the integrity of the cable and visually check for abuse. Second, assure the
system is cleaned and checked periodically for damage following our listed precautions. Last
of all, set a schedule for periodic calibrations by Houston Digital Instruments, if required.
