Type 75 - T75 Precision Relay - Fixed Negative Bias (4psi)
The Bellofram Precision Controls Type 75 Fixed Negative Bias Precision Relay uses an internal 4 ± 1 psig bias spring to automatically subtract approximately 4 psi from the incoming pneumatic signal. The relay combines this negative-bias function with stable, high-flow pressure control using a balanced supply valve, rolling diaphragm, and aspirator tube. At the stated test condition, forward flow is about 41 SCFM and exhaust capacity is about 7 SCFM. This configuration is useful for electronic-control interfaces, volume boosting, tensioning, clutch and brake control, roll loading, cylinder control, and other applications requiring a controlled pressure offset below the input signal.
Features:
- Balanced Valve Design
- High Flow Capacity
- Field Serviceable
- Multiple Output Ratios
- Negative Biasing Option
- Can Be Disassembled and Serviced Without Removing from Line
- Gas Flow Control
- Tensioning Control
- Clutch and Brake Controls
- Volume Boosting
- Dancer Roll Loading
- Calendar Roll Loading
- Cylinder Bucking Control
- Valve Motor Loading
- Electronic Control Applications (Negative Biasing Version)
Maximum Supply Pressure
250 psig (17.2 BAR)
Pressure Ranges
0-150 psig
(0–10.3 BAR)
(0–10.3 BAR)
Port Sizes
1/4", 3/8", 1/2"
NPT, BSPP, BSPT
NPT, BSPP, BSPT
Sensitivity
1/4" H2O (6.4mm)
Forward Flow Capacity
41 SCFM (1150 LPM)
@ 20 psig (1.4 BAR)
signal and 100 psig
(6.9 BAR) supply
@ 20 psig (1.4 BAR)
signal and 100 psig
(6.9 BAR) supply
Exhaust Capacity @ 5 psig (0.4 BAR) above setpoint
7 SCFM (170 LPM)
@ 10 psig (0.69 BAR)
above a 20 psig
(1.4 BAR) setpoint
@ 10 psig (0.69 BAR)
above a 20 psig
(1.4 BAR) setpoint
Temperature Range
-40 to 200˚F
(-40 to 93˚C)
(-40 to 93˚C)
Total Air Consumption @ Maximum Output
<12 SCFH (5.7 LPM)
Materials of Construction
aluminum, brass, carbon steel, stainless steel, acetal, nitrile
Supply pressure sensitivity
< 0.6 psig (0.01 BAR)
per 50 psig (1.4 BAR)
change in supply pressure
per 50 psig (1.4 BAR)
change in supply pressure
Maximum Signal
150 psig(10.3 BAR)
Ratio of Accuracy for 12 psig span
< 2% (1:1)
Find Your Part Number
Not sure? Call for help. Phone: 304-387-1200
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