Cameron Barton 199 - Section 1 - Introduction

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SECTION 1 - INTRODUCTION
1-1. General
The Barton
®
Model 199 Differential Pressure Unit (DPU) (see Figure 1 -1) is a
mechanical device which accurately measures differential pressure relative to a
gas or liquid flowing through a process system, or to the level of a liquid con-
tained in a process vessel.
For process ow measurements, the DPU is connected across a primary device
(a venturi, an orice plate or a ow tube) located in the process system.
For liquid level measurements, the DPU may be connected in a variety of ways
to measure the difference in pressure caused by variations in the level of the
liquid in the process vessel
.
1-2. Product Description
The Model 199 DPU is a dual
bellows assembly enclosed within
HP Housing
LP Housing
Connection
Pressure
pressure housings. The dual
bellows assembly consists of two
opposing internally connected liq-
Venting
uid-lled bellows, a center plate,
Connection
range springs, overrange valves,
Torque Tube
and a torque tube assembly.
Shaft
The pressure housings are con-
nected by Pipe or tubing to the
primary device located in the sys-
Mounting
tem piping. Variations in differen-
Bracket
tial pressure within the pressure
housings cause the bellows to expand or contract in a linear direction towards
the side having the lowest pressure
.
The linear movement of the bellows is converted into angular rotation when
transmitted to the torque tube shaft by the drive arm and this mechanical mo-
tion actuates the mechanism of the process monitoring instrument.
The process monitoring instrument that is connected to the torque tube as-
sembly may be an indicator, a switch, a transmitter, a recorder, or other process
control device.
1-3. Specications
Torque Tube Rotation (full scale DP).............8° ±10%
Torque Tube Material..................................Beryllium Copper (BeCu)
Temperature Limits ....................................-40°F/°C to +180°F (+82°C)
Maximum Non-linearity:
0-10" w.c. to 0-400" w.c.
(0-25 mbar to 0-993 mbar) .........................±0.5% of full scale with
appropriate linkage
0-401" w.c. to 0-100 psi
(0-996 mbar to 0-6.9 bar) ...........................±0.75% of full scale with
appropriate linkage
Repeatability ..............................................0.20% of full scale DP
Housing Materials/Ranges ..........................Refer to Table 1-1
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