1.0
Description
The Series ‘J’ Pneumatic Switch is a single airline, bleed
type valve with a magnetically actuated flapper. The move-
ment of the magnet assembly causes the switch to change
state, either moving the flapper away from the nozzle allow-
ing the pressure in the line to vent or moving the flapper
against the nozzle causing pressure to build up in the line.
2.0
Principle of Operation
Figure 1 shows the attraction sleeve and magnet in the posi-
tion when the liquid level is such that the attraction sleeve is
below the field of the magnet. In this position, the flapper
has been drawn away from the nozzle by the fall-out spring;
and, air flows faster through the nozzle than it can be sup-
plied through the restriction. The air pressure to the control
valve then drops to zero.
Figure 2 shows the attraction sleeve when it is within the
field of the magnet. When a change in the liquid level
moves the attraction sleeve into the field of the magnet, it
causes the magnet to pull in against the enclosing tube. In
this position, the flapper is held against the nozzle, thus
shutting off the bleed of air. The air pressure to the control
valve builds up to supply pressure. The switch is reversible
with two simple adjustments described on page 4.
NOTE: Clean, dry, regulated air should be used with the pneumatic
switch.
Non-magnetic
enclosing tube
D
R
Non-magnetic
enclosing tube
Reverse
link
position
for
opposite action
R
D
Attraction sleeve
Attraction sleeve
Reverse
link
position
for
opposite action
Bleed
restriction
Air supply
Flapper
Nozzle
To
control
valve
Magnet (swing
out
position)
Falling
level
Bleed
restriction
Air supply
Nozzle
Flapper
To
control
valve
Magnet (swing
in
position)
Rising
level
Figure 1
Attraction sleeve below field of magnet
Figure 2
Attraction sleeve in field of magnet
42-685 Series J Pneumatic Switch Mechanism
3
MAGNETROL [ MAGNETROL INTERNATIONAL, INC. ]
