Dwyer Instruments Series D Installation and Operating Instructions
Bulletin IN-0118
HOLES FOR
FLANGE SCREWS
1/2⬙ CONDUIT
CONNECTION
5-3/4⬙ DIA.
1/4⬙ NPT
1-1/2⬙
1/4⬙ NPT
1-1/8⬙
DA-21
DA-31
DA-41
DA-22
DA-32
DA-42
Series “D” Pressure Controls with Mercury Switches
Specifications - Installation and Operating Instructions
Mercoid® Series “D” Pressure Controls feature hermetically
sealed mercury switches, Bourdon tube power elements, visible
setpoint, adjustable deadband or fixed deadband and pressure
ranges from 0-30” Hg. Vac to 800-8000 psig (345 bar).
FEA TURES
• Visible calibrated dial
• On/off indication
• Adjustable, fixed deadband, or manual reset
• External switch setpoint adjustments
• Minimum deadband is obtainable at any point in the range
• Pressure Ranges of full vacuum to 8000 psig.
• UL listed, CSA approved. Many models FM approved.
• General purpose, weatherproof or explosion-proof
enclosures
• Single or two stage operation
SPECIFICA TIONS
Wetted Materials: Brass, 403 SS, or 316 SS.
Temperature Limit: 180°F (82°C).
Pressure Limit: Maximum pressure of the operating range.
Enclosure Rating: General purpose, weatherproof or explosion-
proof.
Repeatability: ±1% of full operating range.
Switch Type: See circuit chart.
Electrical Rating: See electrical ratings chart.
Electrical Connections: Screw terminal.
Conduit Connection: General purpose: 1/2˝ hole for conduit
hub. Weatherproof: 1/2˝ conduit hub. Explosion-proof: 3/4˝ female
NPT.
Process Connection: General purpose and weatherproof: 1/4˝
male NPT, 1/2˝ male NPT on ranges 15S and 16S. Explosionproof: 1/2˝ male NPT and 1/4˝ female NPT.
Mounting Orientation: Vertical.
Set Point Adjustment: Thumbscrew.
Weight: General Purpose: 4 lb (1.8 kg), weatherproof: 6 lb
(2.7kg), explosion-proof: 8 lb (3.5 kg).
Deadband: See Ranges and Differentials Chart.
INSTALLATION
Location and Mounting
Select a location that is recommended by equipment manufacter
and reasonably free from vibration caused by reciprocating or
rotating machinery. Where excessive vibration occurs, use a
remote connection and mount by means of a mounting bracket or
separable flange (available on order). When in doubt about excessive vibration, use a remote connection. Where pulsations, pressure surges, or water hammer are present, protect the contr ol with
a surge tank or scrubber. Mount all controls vertically and
level.
General Purpose Controls: Install controls prefixed by the let-
ters DA, DAF, DRF, DL, DS, DSF, firmly in a level position. Do not
mount the control by twisting the case; use a wrench on the
square part of the 1/4″ bottom pipe connection. To level, sight
across the two cover screws or check the lower end of the glass
opening in the cover to see that the control is lined up horizontally. On general purpose controls provided with a flange, mount by
means of the three holes in the flange.
2-1/4
[57.15]
6-1/64
[152.8]
MERCOID
CONTROL
1/4 N.P.T.
DIA.
ADJUSTMENT SCREWS
7/8 [22.23]
1/2 [12.7]
CONDUIT HOLE
5/8 [15.88]
1-5/8
[41.28]
ACCESSORIES
Remote Connection
No. 49-62 (300 psi)
No. 49-62HP (to 2500 psi)
MERCOID DIVISION
Mounting Bracket
No. 33-25
Pigtail Siphon
No. 42-52 (300 psi)
No. 42-58 (2,000 psi)
General Purpose
DA-24
DA-34
DA-44
13/64⬙
DIA.
6-1/2⬙ DIA.
DA-23
DA-33
DA-43
BOTTOM CONNECTION
BACK
CONNECTION
General Purpose with
Flange for Surface Mounting
Bulletin IN-0118
Page 2
General Watertight or Weather-Resistant Types: These controls are
prefixed by the letters DAW, DRW, DSW and DLW. They are supplied with
flanged case, bottom connection only, for surface mounting. Again, install
firmly in a level position. Do not mount the control by twisting the case;
use a wrench on the square part of the 1/4″ bottom pipe connection. Be
sure pipe connection is in a vertical position. After cover is properly
attached, with the name plate on bottom of the cover, sight across the
lower end of the glass opening in the cover to see that the control is lined
up vertically. Do not use holes in case bottom for mounting
Explosion-Proof Types: Install controls prefixed by the letters DAH,
DAHF, DRH, DSH, DAE, DRE, DSE, firmly in a level position by means of
mounting lugs attached to the control housing. Line up horizontally by
sighting across the left and right conduit hubs.
Notes: Series D-30, D-230, D-430, D-530 (i.e., DA-31-3, etc.), when used
for steam with operating ranges of 35 psi or higher, must be siphoned to
prevent live steam from entering the Bourdon tube. With high pressure
steam in excess of 100 psi, use a remote connection.
Series D-20, D-220, D-420, D-520 (i.e., DA-21-2, etc.), when incorporate an orifice as standard in the bottom stem to dampen out surges or pulsations.
WIRING
Wire in accordance with local electrical codes or equipment manufacturer’s
instructions.
For general purpose controls, use a short piece of BX between the rigid
conduit and the control so that it will not be subjected to conduit expansion and contraction. Where control is directly connected into load circuit,
it should be connected into hot side of line. For electrical rating, see nameplate attached to control case.
ADJUSTMENTS: How to Set Operating Point
Double Adjustment Types - Fully Automatic
Prefixed by DA, DAF, DAW , DAH,
DAHF - provided with double
adjustments. Adjust the upper
pointer “C” to set the HIGH
PRESSURE POINT for switch
operation. Adjust the lower
pointer “U” to set the LOW
PRESSURE POINT. The difference between the HIGH and
LOW pointers is the operating
differential between “on-off”
switch operation.
Single Adjustment Types - Fully Automatic
Prefixed by DS, DSE, DSF, DSH equipped with a single adjustment.
The single pointer on the scale sets
the pressure where switch operation
occurs. Differential is fixed (not
adjustable). Example setting: Type
DS-21-2, range 0-60 psi: circuit
opens on pressure rise. If pointer is
set at 40 psi, the control will operate
to OPEN circuit at 40 psi and RECLOSE circuit at the fixed differential
of 4 psi.
Semi-Automatic Control with Manual Reset
Prefixed by DR, DRF, DRH, DRE, DRW - with suffix -L or -U. Example: Type
DR-21-2U. A single adjustment sets the operating point for automatic
operation. A push-button reset must be operated manually to restore the
circuit to the original position after automatic operation. Example: Type DA21-2L. Circuit will open 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 reclose until the reset button
has been operated.
Suffix -L denotes control will
operate automatically on an
increase in pressure.
Suffix -U denotes control will
operate automatically on a
decrease in pressure.
U
Double Adjustment
Types - Fully Automatic
Adjustment
Single Adjustment
Types - Fully Automatic
Reset
Semi-Automatic Control
with Manual Reset
C
Single
Adjustment
Manual Lock Type Reset Control
Operates automatically on a decrease of pressure with provision for manual reset when pressure is below set point. Prefixed by DL, DLW, DLE,
DLH. A single adjustment sets the low pressure operating point of the
control at any value on the scale range. The control will operate automatically at the set point only on a drop in pressure. The lock-type feature permits the circuit to be reset and locked in position when pressures ar e below
control setting. The lock remains in effect until the pressure has risen to a
value above the control setting.
Lock then releases and the circuit
is held in the reset position due to
the pressure rise. It will remain in
the reset position until it is called
on to again operate automatically
on a pressure drop to the selected setting.
Two-Stage Pressure Controls - Series D-400
Types DA, DAW, DAH, DAE - with suffixes 421, 423, 431, 433, etc., followed by specification numbers 4122, 4123, 4129, 4132.
This series incorporates two single pole, single throw magnetic mercury
switches, actuated by the same Bourdon tube. The operating point of
each switch is adjustable through an outside adjustment.
The change in pressure which opens and closes each switch at its respective setting is the switch’s fixed differential. The pressure represented by
the difference between the two adjustment pointers is the pressure
“spread” between operation of the two switches. Upper pointer “U” indicates the operating point of the HIGH pressure circuit. Lower point “L”
indicates the operating point of the low pressure circuit.
Switch B
Manual Lock Type
Reset Control
Switch A Low
Reset
Adjustment
High
Upper
Pointer
U
Lower
Pointer
L
Example Setting: Type DA-421, Specification No. 4122, range 0-60 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.
CAUTIONS
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 lbs. 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.
Two-Stage Pressure Controls
Series 400
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