User manual | Model 43

Regulators
Models 43 & 44 Precision Sub-Atmosphere Pressure Regulators
Introduction
Features & Benefits
Barometrically compensated to regulate absolute
pressure ranges (Model 43)
Used for compound (vacuum-pressure) ranges (Model 44)
Precision bellows-sensing elements provide greater sensitivity
Description
The Models 43 and 44 Sub-Atmospheric Pressure Regulators
are pilot-operated regulators with bellows-sensing elements for
use within absolute and compound pressure ranges. The Model
43 is barometrically compensated for use in absolute pressure
ranges, while the Model 44 regulates compound (vacuumpressure) ranges.
Both models use the pneumatic null-balance principle of
operation. As such, imbalances between the regulator setting
and the output are corrected by a pilot circuit that holds the
output pressure constant regardless of wide changes in flow or
supply pressure.
A vacuum pump provides the sub-atmospheric pressures.
In addition, both model series have tapped exhaust connections
for use with this pump.
Operating Characteristics
Standard Supply Pressure
Ambient Temperature Effect (for 50°F [27°C] temperature
change)
Model 43-20 & 43-50: ±1% of regulated pressure
Model 44-20 & 44-50: ±0.1 psi
Model 43L: ±0.03 psi
Pilot-air Consumption (with recommended supply)
Model 43-20 & 44-20: 0.06 scfm
Model 43-50 & 44-50: 0.10 scfm
For L-type instrument, in balanced condition on deadend
service: scfm - 0.003P where P = set pressure in psia
At least 5 psi higher than the maximum desired regulated
pressure
Standard Mounting
Maximum Supply Pressure
In-line pipe or flush panel up to 3/16" thick
(1-3/32 dia. hole req’d for panel mounting)
Model 43-20: 20 psig
Model 43-50: 55 psig
Model 44-20: 35 psig
Model 44-50: 70 psig
Connections
Minimum Supply Pressure
Brass, stainless steel, Neoprene, aluminum, and zinc
1/4" NPT for supply & outlet, all other 1/8" NPT
Materials of Construction
3 psig above regulated output
Overrange Protection
The application of the maximum rated supply pressure to
any connection will not damage the instrument
Ambient Temperature Limits
-40 to 180°F (-40 to 80°C)
Specifications
Resolution Adjustment
Within ± 0.001 Hg of desired pressure setting
Range
Regulator
Body Material
43-20
1-20 psia
brass
43-50
1-50 psia
brass
1
43-20L
0.1" Hg-20 psia
brass
43-50L1
0.1" Hg 50 psia
brass
43A20L1
0.1" Hg-20 psia
aluminum
Model No.
1
43A50L
0.1" Hg 50 psia
aluminum
44-20
Nominal 28" Hg Vac 5 psig
brass
44-50
Nominal 28" Hg Vac 35 psig
brass
Supply Pressure
Minimum: 3 psig above regulated output
1) A constant differential relay is required with these units in order to reach the low pressures listed. For a piped assembly (absolute pressure regulator with
constant differential relay), add 63A to the basic model number (i.e. -43-20L would be designated -43-20L63A).
7.9
7
Regulators
Models 43 & 44 Precision Sub-Atmosphere Pressure Regulators
Dimensional drawings
Mounting Dimensions
7
7.10

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