Pressure Instruments

DOE-HDBK-1132-99

space requirements for installation, operation, maintenance, calibration,

replacement, accessibility, and electrical flexible conduit installation;

vibration-free mounting on available structures;

interference with other commodities;

environmental conditions (radiation, temperature, moisture, noise, etc.).

To provide sufficient slope requirements and thus avoid gas and liquid pocketing

in sensing lines, the required instrument location relative to its process

connection should be as follows:

Instrument Location

Fluid

Elevation

Liquid

Below line connection

Slurry

Below line connection

Steam over 20 psia

Below line connection

Steam under 20 psia

Above line connection

Gas

Above line connection

Instruments that cannot be connected with proper slope should be provided with

accessible vent and drain points.

Vent and drain connections for hazardous or radioactive processes

should have provisions for safe disposal of fluid.

Where practicable, instrument mounting heights should be 4 feet,

6 inches from the floor.

Pressure Instruments .

4.9.3

Condensate pots are not necessary for a sensing element that has a

negligible dynamic displacement (e.g., a force-balance transmitter). If

displacement is not negligible and process fluid is steam, other

condensable fluid, or other fluid that may flash, condensate pots should

be used. If condensate pots are used, their volume should be at least

three times the volume of the displaced volume.

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