Example Setting:
Type DA-421, Specification No. 4122, range 0 to 60 psi. With lower
pointer “L” set at 25 psi and upper pointer “U” set at 50 psi, both circuits will be closed
when pressure is 25 psi and lower. When pressure rises to 26 psi, mercury switch A will
open its circuit. When pressure rises to 50 psi, mercury switch B will open its circuit.
Both switches remain open above this setting. The fixed differential (sensitivity) of
each switch for this particular range is 1 psi. Upon a drop in pressure, mercury switch
“B” will close its circuit at 49 psi; mercury switch “A” will close its circuit at 25 psi.
LOCKING DEVICE
When the control has been adjusted to desired range, the locking bar may be inserted
between the adjustment screws with slot passing over the hole in the lug. By placing
a sealing wire between the locking bar and the hole in the lug protruding from the
adjustment assembly, adjustments cannot be tampered with.
For DAF, DRF, DSF, DAW, DRW, DSW, the adjusting knob cover may be sealed in
place with sealing wire through the cover bolt hole. For DAH, DSH, sealing wire may
pass through locking bar and hole in hub above the adjusting knobs.
Do not exceed maximum adjustment/operating range of control.
Remove control if higher pressures are required.
Do not fail to use a siphon on steam where range is 35 lb or more.
Control movement must not be oiled.
Do not overload — note electrical rating on nameplate and be sure
total current passing through switch is within specified rating.
Do not tamper with switch wires. Position of these wires is essential
to proper operation. Tampering with these wires will void warranty.
CAUTION
CAUTION
CAUTION
CAUTION
Controls with Mercury Switches
Adjustable Differential
Double Adjustment for setting both ‘on
and ‘off” operating points Maximum
Differenial - full-scale. Minimum
Differential listed below.
Fixed Differenital
Single Adjustment Adjustable
operating point. Differential
fixed NOT ADJUSTABLE
APPLICATION
Bourdon tube Material
Adjustable Operating Range
psig
Range
Number
DA-31
DA-531
DS-231
Brass Bourdon Tubes
0-30 Hg VAC
10 in Hg VAC 12
1/8 to 15 psig
1/8 to 20 psig
1 to 35 psig
25 in Hg VAC 50
2 to 60 psig
5 to100 psig
5 to 150 psig
10 to 200 psig
10 to 300 psig
2
3
1
3A
4
27
5
6
7
8
9
2˝ Hg
1 psig
1 psig
1 psig
1.75 psig
3.5 psig
3 psig
3.75 psig
6 psig
8 psig
12 psig
1 in Hg
0.5 psig
0.5 psig
0.5 psig
0.75 psig
2 psig
1 psig
2 psig
3 psig
3.5 psig
6 psig
0.2 in Hg
2 oz
2 oz
2 oz
4 oz
7 oz
6 oz
7 oz
8 oz
12 oz
16 oz
DA-21
DA-521
DS-221
403 Stainless Steel
Bourdon Tubes
30 in Hg VAC 60
30 in Hg VAC 75
2 to 60 psig
5 to 100 psig
10 to 200 psig
10 to 300 psig
40 to 350 psig
25 to 600 psig
50 to 1000 psig
100 to 1500 psig
300 to 2500 psig
500 to 5000 psig
800 to 8000 psig
25S
26S
5S
6S
8S
9S
9AS
10S
11S
12S
13S
15S
16S
6 psig
8 psig
4 psig
6 psig
8 psig
14 psig
14 psig
25 psig
60 psig
90 psig
150 psig
450 psig
750 psig
3 psig
4 psig
2.5 psig
3 psig
4 psig
7 psig
7 psig
15 psig
40 psig
50 psig
100 psig
200 psig
400 psig
12 oz
12 oz
0.5 psig
0.75 psig
0.75 psig
1 psig
1 psig
2.5 psig
10 psig
12 psig
45 psig
150 psig
200 psig
DA-41
DA-541
DS-241
316 Stainless Steel
Bourdon Tubes
30 in Hg VAC 75
5 to 75 psig
10 to 100 psig
10 to 150 psig
10 to 300 psig
30 to 400 psig
75 to 800 psig
100 to 1000 psig
200 to 2500 psig
26E
23E
6E
24E
9E
21E
22E
11E
13E
7 psig
3 psig
7 psig
6 psig
18 psig
30 psig
75 psig
100 psig
210 psig
35 psig
2 psig
3.5 psig
3 psig
5 psig
15 psig
35 psig
45 psig
110 psig
14 oz
0.4 psig
14 oz
0.75 psig
3 psig
5 psig
12 psig
18 psig
50 psig
Note:
Differentials listed are for SP-ST operation only. When controls incorporate two mercury switches for double throw or two pole operation, the
differentials are approximately double those shown for standard single pole, single throw controls.
