Dwyer 1950G - Manual (Page 2)

1-11/16
[42.86]
1/8˝ NPT LOW
PRESSURE PORT
5-7/16
[138.1]
4-7/8
[123.8]
1/8˝ NPT HIGH
PRESSURE PORT
1/2˝ NPT
ELECTRICAL
CONDUIT
CONNECTION
RANGE
ADJUSTMENT
SCREW
17/64˝ DIA. MTG. HOLES (2)
EXTERNAL GROUND
3-1/2
[88.90]
CAPTIVE
SCREW
13/32
[10.312]
VENT DRAIN
PLUG
1-17/32
[38.89]
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 and 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.
For units supplied with both internal and external bonding terminals, the
ground screw inside the housing must be used to ground the control. The
enternal 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.
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.
Bulletin E-57G
Page 2
1950G Switch Outline Dimensions
DWYER INSTRUMENTS, INC.
Phone: 219/879-8000 www.dwyer-inst.com
P.O. Box 373 • Michigan City, IN 46360-0373, U.S.A. Fax: 219/872-9057 e-mail: [email protected]
Fig. A
Fig. B
+ -
©Copyright 2012 Dwyer Instruments, Inc. Printed in U.S.A. 2/12 FR# 28-440332-10 Rev. 9
LOCKWASHER
SCREW
CONDUCTOR
CLAMP PLATE
CLAMP
FRONT VIEW DETAIL SIDE VIEW DETAIL