ADJUSTMENTS: HOW TO SET OPERATING POINT
Double Adjustment Types - Fully Automatic:
With double-adjustment switches (prefixed DA, DAH or
DAW), adjust the upper pointer “U” to set HIGH PRESSURE
POINT for switch operation and adjust the lower pointer “L”
to set LOW PRESSURE OPERATING POINT. The differ-
ence between the “U” and “L” pointers is the operating dif-
ferential between “on-off” switch operation.
Semi-Automatic Control with Manual Reset:
Models prefixed DR, DRH, DRW and with suffix L or U
(example: DR-7021-153U) have a single adjustment that
sets the operating point for automatic operation. A push-
button reset must be operated manually to restore the cir-
cuit to the original position after automatic operation.
Example: Type DR-7021-153L has a circuit that opens
automatically on a pressure rise to the pressure indicated by
the pointer on the scale; no matter how much the pressure
drops, the circuit will not re-close until the reset button is
operated. Suffix L denotes control will operate automati-
cally on an increase. Suffix U denotes control will operate
automatically on an decrease.
SINGLE ADJUSTMENT TYPES—FULLY AUTOMATIC:
Models prefixed DS, DSH, DSW, N3DSW are equipped with
a single adjustment. Differential is fixed (not adjustable). The
single pointer on the scale sets the pressure at which switch
operation occurs. Differential is listed in chart indicates
approximate fixed differential.
LOCKING DEVICE
When the control has been adjusted to desired range, the
locking bar may be inserted between the adjustment
screws with the slot passing over the projecting lugs. By
placing a sealing wire between the locking bar and the hole
in the lug protruding from the adjustment assembly, adjust-
ments cannot be tampered with.
For DRF, DAW, DRW, adjusting knob cover may be sealed
in place with sealing wire through cover bolt hole. For DAH,
sealing wire may pass through locking bar and hole in hub
above adjusting knobs.
DELRIN
®
BUSHED MOVEMENT “B”
Delrin
®
bushed movements prolong control life by alleviating
wear of metal surfaces due to excessive vibration and/or
pulsation. They also prolong switch life in environments
where corrosion may be a factor. Models with Delrin move-
ments are identified by the letter “B after the suffix number.
Examples: -153B, -153UB, etc.
*
Delrin is a registered trademark of E. I. DuPont de Nemours & Co.
CONTROL NUMBER
Part of the control number (the fourth number in the sequence)
identifies the type of control case. Digit 1 of 7021, 7031, 7041,
denotes a plain case with bottom connection. Digit 2 of 7022,
7032, etc., denotes a plain case with back connection. Digit 3 of
7023, 7033, 7043, etc., denotes a flanged case with bottom con-
nection. Digit 4 of 7024, 7034, etc., denotes a flanged case with
back connection. (Digit 3 of 7321, 7331, 7341, etc., denotes her-
metically sealed snap switch.)
CIRCUITS (SWITCH OPERATION)
S
uffix number after control number denotes switch action:
Suffix -153 designates SPDT; one circuit closes as other circuit
opens.
Suffix - 804 designates two SPDT switches; two close,
two open.
Double-Adjustment Types
Fully Automatic
Bulletin IN-523
Page 3
Semi-Automatic Types
with Manual Reset
Delrin
®
Bushed Movement “B”
PIVOT POINT
BEARINGS,
TOP & BOTTOM,
BUSHED WITH DELRIN
SWITCH CARRIER
STOP POST SLEEVED
WITH DELRIN
DELRIN PIN
DELRIN PIN
BAR LINK
DELRIN BRUSHED
PIVOTAL END
BEARING &
CONNECTION
BAR PIN OF
DELRIN
Switch Indicator
Orange indicates
on high
U - Upper
Pointer
L - Lower
Pointer
Single
Adjustment
Switch
Operating
Indicator
Single Adjustment Types Fully Automatic
Adjustment
Reset