Table 7 Zero Corrects Procedure For Transmitters With A Small Differential Pressure Span; Figure 8 Leveling Transmitters - Honeywell ST 3000 User Manual

Mount transmitter vertically to assure best accuracy. Position spirit balance on pressure
connection surface of AP body.
CAUTION
The mounting position of a model STA122 or STA922 Absolute Pressure Transmitter or a
model STD110 Draft Range Differential Pressure Transmitter is critical as the transmitter
spans become smaller. A maximum zero shift of 2.5 mm Hg for an absolute transmitter or 1.5
in H 2 O for a draft range transmitter can result from a mounting position which is rotated 90
degrees from vertical. A typical zero shift of 0.12 mm Hg or 0.20 in H 2 O can occur for a 5
degree rotation from vertical.
Differential Pressure Transmitters
For a transmitter with a small differential pressure span (Model STD110, for example), you must ensure
that the transmitter is vertical when mounting it. You do this by leveling the transmitter side-to-side and
front-to-back. See Figure 8 for suggestions on how to level the transmitter using a spirit balance. You must
also zero the transmitter by following the steps in Table 7 below.

Table 7 Zero Corrects Procedure for Transmitters with a Small Differential Pressure Span

Step
1 Attach the transmitter to the mounting bracket but do not completely tighten the mounting
bolts.
2 Connect a tube between the input connections in the high pressure (HP) and low pressure
(LP) heads to eliminate the affects of any surrounding air currents.
10/05
In-line models

Figure 8 Leveling Transmitters

ST 3000 HART Transmitter Release 300 User Manual
4— Installation - Mounting ST 3000 Transmitter
Action
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