TUFFY
®
Liquid Level Controls
with Pneumatic Switches
®
INSTRUCTION MANUAL AND PARTS LIST
DESCRIPTION
Tuffy liquid level switches are designed for horizontal mount-
ing in a tank or vessel through threaded or flanged pipe con-
nections. Standard models are equipped with a three-
port/two-position valve, actuated by a magnetically actuated
pivoted cam mechanism. This instruction manual covers
Tuffy level controls which have pneumatic switches. For
Tuffy controls with electric switches, please consult Bulletin
BE 44-605.
OPERATING PRINCIPLE
Figures 1 and 2 illustrate the simple Magnetrol operating
principle. Switching action is obtained through the use of a
magnet attached to a float and a switching mechanism.
These two basic component assemblies are separated by a
non-magnetic, pressure tight barrier.
APPLICATIONS
Tuffy is recommended as a high or low alarm switch for
clean liquid applications only.
(For Tuffy controls with electric switches, consult bulletin BE 44-605)
OPERATING CYCLE
At a “low operating level” of liquid in a tank or vessel (refer
to Figure 1), the float moves the magnet upward and into
the field of the switch mechanism magnet. As a result, the
magnets repel causing the pivot arm and valve plunger to
move so that air is allowed to pass from air inlet A to air out-
let C. As liquid level rises, for “High Operating Level” indi-
cation (refer to Figure 2), the float moves the magnet down-
ward until the switch mechanism magnet reverses position,
allowing the valve plunger to move so that air is allowed to
pass from air inlet B to air outlet C.
For direct acting low level operation, air inlet A is closed off
when liquid level increases. Conversely, for direct acting
high level operation, air inlet B is closed off when liquid level
recedes.
For reverse acting operation, air inlet A is used for high level
and air inlet B is used for low level. The air inlet that is not in use
should be plugged to prevent foreign materials from entering.
UNPACKING
Unpack the instrument carefully. Inspect all units for dam-
age. Report any concealed damage to carrier within 24
hours. Check the contents of the packing slip and purchase
order. Check and record the serial number for future refer-
ence when ordering parts.
MODEL IDENTIFICATION
Air inlet B
(no air flow)
Air inlet A
Valve body
Air outlet C
Pivot arm
Falling level
Float
Pivot
Magnets
Magnet
pivot
Tuffy body
(non-magnetic)
Spring
Valve
plunger
Figure 1: Low level operation – direct acting
Air inlet B
Air inlet A
(no air flow)
Valve body
Air outlet C
Pivot arm
Rising level
Float
Pivot
Magnets
Magnet
pivot
Tuffy body
(non-magnetic)
Spring
Valve
plunger
Figure 2: High level operation – direct acting
SPECIFIC GRAVITY
PNEUMATIC SWITCH
0
0,6 minimum
4
0,4 minimum
0
0
0
0
9
1 0
3
6
