Fisher 67FR Pressure Regulator Report

by

Clifton M Posey

Connection Diagram:

PIPI

Fisher 67FR

40 psi air supply

0 - 30 psi

As Found:

0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.000.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

f(x) = 0.493571428571429 x − 2.36666666666667R² = 0.999754326334193

Fisher 67FR 'As Found'

Pressure (psi)

Tota

l Tur

ns (s

ince

5 p

si)

As Left:

10.00 15.00 20.00 25.00 30.00 35.000.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

f(x) = 0.503422116192497 x − 2.58529026659389R² = 0.999317682257317

Fisher 67FR 'As Left'

Pressure (psi)

Tota

l Tur

ns (s

ince

5 p

si)

0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.000.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

f(x) = 0.502857142857143 x − 2.53333333333333R² = 0.999595549321469

Fisher 67FR 'As Left' (rerun)

Pressure (psi)

Tota

l Tur

ns (s

ince

5ps

i)

Fisher 67FR Schematic

Adjustment Screw

Bonnet

Primary Spring Seat

Bonnet Vent

Primary Spring

Diaphragm AssemblyDiaphragmValve PinValve SeatValve Outlet PortInlet PortValve Spring SeatValve SpringValve Spring Adapter (has 4 ports)

Filter

Filter Seat

Filter Screw

Drain Valve

Hooke’s Law:

F = kx = Pressure x AreaArea = r2 of the diaphragm = 3.14 x (2.115 in/2)2 = 3.51326 in2

F = kx = PA

k(12.5 turns – 0 turns) / 24 turns/inch) = (30 psi – 5 psi) x 3.51326 in2

k = 168.636 lb/inAs Compression Increases:

As the compression is increased to the spring the force it exerts on the diaphragm and valve increases, resulting in the maximum pressure transmitting through the regulator to increase. When the adjusting screw is tightened on top of the regulator, the large spring just below it transfers that higher force to the diaphragm and valve through the valve stem, requiring a higher force to throttle the valve closed and equalize the pressure on the diaphragm resulting in a higher output pressure maintained as long as the input pressure exceeds that pressure.

As Compression Decreases:

As the compression is decreased to the spring the force it exerts on the diaphragm and valve decreases, resulting in the maximum pressure transmitting through the regulator to decrease. When the adjusting screw is loosened on top of the regulator, the large spring just below it transfers that lower force to the diaphragm and valve through the valve stem, requiring a lower force to throttle the valve closed and equalize the pressure on the diaphragm resulting in a lower output pressure maintained as long as the input pressure exceeds that pressure.

Regulator Function:

A regulator is a valve used to maintain a constant pressure which is different than its upstream pressure. This pressure is regulated by setting a “set point” through adjustment of the spring compression on a diaphragm located in the downstream section of the regulator. This regulator (Fisher 67FR) is a pressure reducing regulator, commonly used to regulate instrument pressures which are lower than supply pressures.

Fisher 67FR connected on the bench

Close up of Fisher 67FR Low Pressure Side High Pressure Side

Close up of valve assembly Diaphragm Measurement Gauge

Lab Notes