Dwyer H3 - Manual (Page 2)

INSTALLATION
1. LOCATION: Select a location where the temperature limit of 220°F
(104°C) will not be exceeded. Locate the switch as close as possible to
the pressure source for best response. Longer lengths of tubing will not
affect the accuracy of the actuation point but can increase response time
slightly.
2. MOUNTING: Avoid mounting surfaces with excess vibration which
could cause false actuation when pressure is near set-point. Attach
switch with two 3/16˝ screws or bolts (not included) through mounting
bracket. Normal position is with housing vertical.
3. PRESSURE CONNECTION: Connect source(s) of pressure, vacuum
or differential pressure to the 1/8˝ NPT ports as follows:
A. Differential Pressures – Connect higher pressure to High Pressure
port (bottom) and lower pressure to Low Pressure port (side).
B. Pressure Only – Connect a single positive pressure to High Pressure
port on bottom and leave Low Pressure port on side vented to
atmosphere.
C. Vacuum Only – Connect a single negative (vacuum) pressure to Low
Pressure port on side and leave High Pressure port on bottom vented to
atmosphere.
4. ELECTRICAL CONNECTIONS: Either one or two SPDT snap
switches are provided with normally open contacts closing and normally
closed contacts opening when pressure or vacuum increases beyond
the set-point.
A. Wire in accordance with local electrical codes.
B. Wire lead models – Thread wires through conduit and connect to
leads from snap switch(es).
Black=Common, Red=Normally Closed, Blue=Normally Open
C. Terminal block models – Loosen screws on terminal block(s), insert
stripped and tinned wires in side openings and tighten screws.
Black=Common, Red=Normally Closed, Blue=Normally Open
EC-Type Certificate Installation Instructions:
Cable connection
The cable entry device shall be certified in type of explosion protection
flameproof enclosure “d”, suitable for conditions of use and correctly
installed. For ambient temperatures over 70°C, cable and cable glands
suitable for at least 95°C shall be used.
Conduit connection
An Ex d certified sealing device such as a conduit seal with setting
compound shall be provided immediately to the entrance of the valve
housing. For ambient temperatures over 70°C, the wiring and setting
compound in the conduit seal shall be suitable for at least 95°C.
D. Ground Screws – Three grounding connections are furnished; one
inside housing with green headed machine screw, one on the exterior
housing directly below the conduit entry with green headed machine
screw, and the third is opposite the low pressure connection on the
exterior with threaded stud and nut. Use any one.
E. ATEX units only: The “T” class is dependent upon the media or
ambient temperature, whichever is higher. The approved ratings are -
20°C ≤ T amb ≤ 75°C T6.
Replace cover after wiring connections are complete.
CAUTION: Make sure conduit or cable are properly sealed. Electrical
components must be kept free of moisture, including condensation, at
all times. To prevent ignition of hazardous atmosphere, disconnect the
device from the supply circuit before opening. Keep assembly tightly
closed when in operation.
ADJUSTMENT
1. To change the set-point, connect tubing or piping from high pressure
port on bottom to one leg of a tee. Connect the second leg to a pressure
gage of known accuracy and in an appropriate range. The third leg
should be connected to a controllable pressure source.
2. Connect a volt/ohm meter or other circuit tester to snap switch to
indicate when switching occurs.
3. Slowly apply pressure to the system and note the pressure at which
switching occurs, If adjustment is necessary, turn the adjustment screw
(located internally at center next to snap switch) clockwise to raise or
counterclockwise to lower the actuation point. When the required setting
has been reached, exercise the switch through two or three additional
cycles to verify consistent operation.
MAINTENANCE
The moving parts of these switches need no maintenance or lubrication.
The set-point is the only user adjustment. On models with optional drain
fitting, periodically rotate small captive screw from side to side several
times to keep drain path clear. Repairs to be conducted by Dwyer
Instruments, Inc. Units in need of repair should be returned to the factory
prepaid.
Limited Warranty: The Seller warrants all Dwyer Instruments, Inc. and equipment to be free from defects in workmanship or material under normal use and service for a period of one year from date of shipment. Liability under this warranty is
limited to repair or replacement F.O.B. factory of any parts which prove to be defective within that time or repayment of the purchase price at the Seller’s option provided the instruments have been returned, transportation prepaid, within one
year from the date of purchase. All technical advice, recommendations and services are based on technical data and information which the Seller believes to be reliable and are intended for use by persons having skill and knowledge of the
business, at their own discretion. In no case is Seller liable beyond replacement of equipment F.O.B. factory or the full purchase price. This warranty does not apply if the maximum ratings label is removed or if the instrument or equipment is
abused, altered, used at ratings above the maximum specified, or otherwise misused in any way.
THIS EXPRESS LIMITED WARRANTY IS IN LIEU OF AND EXCLUDES ALL OTHER REPRESENTATIONS MADE BY ADVERTISEMENTS OR BY AGENTS AND ALL OTHER WARRANTIES, BOTH EXPRESS AND IMPLIED. THERE ARE NO
IMPLIED WARRANTIES OF MERCHANTABILITY OR OF FITNESS FOR A PARTICULAR PURPOSE FOR GOODS COVERED HEREUNDER.
Buyers Remedies: THE BUYER’S EXCLUSIVE AND SOLE REMEDY ON ACCOUNT OF OR IN RESPECT TO THE FURNISHING OF NONCONFORMING OR DEFECTIVE MATERIAL SHALL BE TO SECURE REPLACEMENT THEREOF
AS AFORESAID, THE SELLER SHALL NOT IN ANY EVENT BE LIABLE FOR THE COST OF ANY LABOR EXPENDED ON ANY SUCH MATERIAL OR FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES TO ANYONE
BY REASON OF THE FACT THAT IT SHALL HAVE BEEN NON-CONFORMING OR DEFECTIVE.
EXTERNAL
GROUND
SCREW
DRAIN /
BREATHER
TERMINAL
BLOCK
SET-POINT
ADJUSTMENT
SCREW
INTERNAL
GROUND
SCREW