Dwyer 1950G Serie Especificaciones Técnicas – Instrucciones De Instalación Y Operación página 2

17/64˝ DIA. MTG. HOLES (2)
RANGE
ADJUSTMENT
EXTERNAL GROUND
SCREW
1/2˝ NPT
ELECTRICAL
CONDUIT
CONNECTION
1/8˝ NPT HIGH
LOW PRESSURE
PRESSURE PORT
1-11/16
[42.86]
1950G Switch Outline Dimensions
INSTALLATION
1. Select a location free from excess vibration and corrosive atmospheres where
temperatures will be within the limits noted under Physical Data on page 1. Switch
may be installed outdoors or in areas where the hazard of explosion exists. See page
1 for specific types of hazardous service.
2. Mount standard switches with the diaphragm in a vertical plane and with switch
lettering and nameplate in an upright position. Some switches are position sensitive
and may not reset properly unless they are mounted with the diaphragm vertical.
3. Connect switch to source of pressure, vacuum or differential pressure. Metal tubing
with 1/4˝ O.D. is recommended, but any tubing which will not restrict the air flow can be
used. Connect to the two 1/8˝ female NPT pressure ports as noted below.
A. Differential pressures - connect pipes or tubes from source of greater pressure to
high pressure port marked HIGH PRESS, and from source of lower pressure to low
pressure port marked LOW PRESS.
B. Pressure only (above atmospheric pressure) - connect tube from source of
pressure to high pressure port. The low pressure port is left open to atmosphere.
C. Vacuum only (below atmospheric pressure) - connect tube from source of vacuum
to low pressure port. The high pressure port is left open to atmosphere.
4. To make electrical connections, remove the three hex head screws from the
cover and after loosening the fourth captive screw, swing the cover aside. Electrical
connections to the standard single pole, double throw relay and AC supply voltage
connections to the unit, are provided by means of terminals marked "COM", "NO",
"NC", "~" and "~" (See Fig. A). Electrical connections to the standard single pole,
double throw relay and DC supply voltage connections to the unit, are provided by
means of terminals marked "COM", "NO", "NC", "+" and "-" (See Fig. B.). The normally
open contacts close and the normally closed contacts open when pressure increases
beyond the setpoint. Switch loads for standard models should not exceed the maximum
specified current ratings as stated on page 1. For ATEX, IECEx compliance, cables
and cable glands suitable for temperature of at least 95°C shall be used. The cable
entry device shall be of certified flameproof type, suitable for the conditions of use and
be correctly installed. Refer to Certificate No.: IECEx DEK 11.0092X for conditions of
safe use for IECEx Compliant units. Switch capabilities decrease with an increase in
ambient temperature, load inductance, or cycling rate.
DWYER INSTRUMENTS, INC.
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A.
3-1/2
[88.90]
4-7/8
[123.8]
5-7/16
[138.1]
VENT
1/8˝ NPT
DRAIN
PLUG
PORT
1-17/32
[38.89]
CAPTIVE
SCREW
13/32
[10.312]
For units supplied with both internal and external bonding terminals, the ground screw
inside the housing must be used to ground the control. The internal bonding screw is
for supplementary bonding when allowed or required by local code. When external
bonding conductor is required, conductor must be wrapped a minimum of 180° about
the external bonding screw. See below.
FRONT VIEW DETAIL
ADJUSTMENT
To change setpoint:
A. Remove the plastic cap and turn the slotted Adjustment Screw at the top of the
housing clockwise to raise the setpoint pressure and counter-clockwise to lower the
setpoint. After calibration, replace the plastic cap and re-check the setpoint.
B. The recommended procedure for calibrating or checking calibration is to use a
"T" assembly with three rubber tubing leads, all as short as possible and the entire
assembly offering minimum flow restriction. Run one lead to the pressure switch,
another to a manometer of known accuracy and appropriate range, and apply
pressure through the third tube. Make final approach to the setpoint very slowly. Note
that manometer and pressure switch will have different response times due to
different internal volumes, lengths of tubing, fluid drainage, etc. Be certain the switch
is checked in the position it will assume in use, (i.e. with diaphragm in a vertical
plane) and switch lettering and Dwyer nameplate in an upright position.
C. For highly critical applications check the setpoint adjustment and if necessary,
reset it as noted in step A.
MAINTENANCE
The moving parts of these switches need no maintenance or lubrication. The only
adjustment is that of the setpoint. Care should be taken to keep the switch reasonably
clean. Periodically the vent drain plug should be rotated then returned to its original
position. This will dislodge deposits which could accumulate in applications where
there is excessive condensation within the switch. Repairs to be conducted by Dwyer
Instruments, Inc. Cover bolts are Class 10.9 35 mm long.
Phone: 219/879-8000
Fax: 219/872-9057
Bulletin E-57G
Fig. A
+ -
Fig. B
LOCKWASHER
CONDUCTOR
SCREW
CLAMP PLATE
CLAMP
SIDE VIEW DETAIL
www.dwyer-inst.com
e-mail: info@dwyermail.com
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