Dwyer 477 User Manual
Page 2
INSTRUCTIONS
Battery Installation
The unit is shipped with a separate 9 volt alkaline battery which must be installed before operation. Remove the two
screws holding the bottom endcap in the place and remove it. Connect the battery to the enclosed battery clip observ-
ing correct polarity. Be careful not to trap wires between the battery, case or foam pads which retain the battery. This
could make it difficult to install the battery or remove it later for replacement. Be sure the rubber gasket is properly seat-
ed in the gasket channel and replace endcap. Note that the endcap will only fit one way because the holes are slight-
ly off-center. Place the “Z” shaped wrist strap clip in one of the screw recesses and replace the screws. Do not over-
tighten. Attach wrist strap to clip.
When battery replacement becomes necessary, use only a 9 volt alkaline type such as a Duracell
®
MN1604, Eveready
®
522 or equivalent. Zinc-carbon types, often labeled Heavy-duty are not recommended because of the increased poten-
tial for leakage. Alkaline batteries are also a better value because they last up to three times longer in this device.
On-Off Operation
The on-off control is a toggle function. Press the ON/OFF key once to turn unit on; again to turn it off. If the manome-
ter is left on with no activity for approximately 20 minutes, unit will turn itself off to conserve the battery.
Display Backlight
The Model 477 includes a display backlight to allow use in the dark or in poor lighting conditions. Units must be
switched off before this feature can be activated. Next, press and hold the ON/OFF key down. After about 1 second
the backlight will come on and remain lighted for approximately 2 minutes after which it will turn itself off to conserve
battery life.
Zeroing Pressure Reading
Potential inaccuracy due to temperature effects can be minimized by re-zeroing immediately before use. To zero the
display, vent both ports to atmosphere so no pressure is applied to either port. Press the ZERO/STORE key and - - -
- will be momentarily displayed as zeroing occurs. Zeroing is not possible when the memory mode is in use. It must be
done before selecting that function.
If the unit is accidently zeroed with pressure applied to one of the ports, internal circuitry might detect an error and dis-
play ALARM 1 or ALARM 2 at the top of the readout area. Additionally, if the ports are then vented, the audible over-
pressure alarm may sound continuously. This will not normally cause harm it the maximum pressure has not been
exceeded. To correct the fault, vent the pressure ports to atmosphere and press the ZERO/STORE key to zero the unit.
The fault will then be corrected.