Dwyer HM28 User Manual
Operating instructions
Digital handheld
pressure gauge
HM28
Contents
1 Description.......................................4
2 Safety details ...................................4
3 Operating .........................................4
3.1 Switching on and off ........................4
3.2 Pneumatic connection .....................4
3.3 Operating modes .............................4
3.4 Configuration ...................................6
3.5 RS 232 mode ................................... 7
3.6 Battery change ..............................10
3.7 Recalibration..................................10
4 Specifications ................................ 10
4.1 Technical data ............................... 10
4.2 Measuring ranges ..........................12
4.3 Mains supply unit connection ........12
5 Maintenance ..................................12
6 Warning messages and faults .......13
7 Accessories ...................................13
8 Calibration instructions ..................14
2
Operating instructions
ON = On
OFF = Off
MODE = Select operating mode
- Pressure measurement
- Min./Max.
- Leak rate
- Datalogging
CLEAR/ZERO = Zero setting
PRINT/HOLD = Print and freeze display
START/STOP = Data recording / printing
SET = Select config. modes
SELECT = Select config. data
c Matrix display
d Connection for pneumatic hoses
e Connection for plug-in power supply unit
f Connection for RS 232 interface
d
c
e
f
Important!
Please note warning symbol
in the operating instructions.
Copyright (c) by LOVE CONTROLS.
The contents of this publication may not be
copied without the express permission of
LOVE CONTROLS.
Subject to dimension and design changes.
3
1 Description
The „LOVE CONTROLS“ handheld pressure
gauge HM28 is a digital pressure measuring
instrument with integrated pressure sensor
for the measurement of differential, relative or
absolute pressures and vacuum. Its versatile
range of functions and high precision makes
it suitable for a wide range of applications.
Configuration possibilities:
• Autom. switching off, selectable time
• Selectable resolution and damping
• Selectable units of time
• Selectable measurement units
• General reset to standard setting
• Selectable data transfer rate
• Configuration printout
• Selectable measuring intervals
2 Safety details
Switching off Press the OFF key, or auto-
matic switching off 1,10 or 60
min after the last keystroke.
In case of a temperature change the instrument
requires at least 30 minutes to adjust to the
new ambient temperature.
3.2 Pneumatic connection
For measuring ranges up to 7000 mbar, 4/6
mm or NPT 1/8" connectors can be connected
depending on model. Higher ranges are
equipped with NPT 1/8".
Ensure correct connection of the pneumatic
hoses!
+P high pressure
S- low pressure (not available
with the absolute and relative
pressure version)
The pressure values stated on the rating plate
and mentioned in these operating instructions
must not be exceeded otherwise the pressure
sensor can be destroyed.
Do not use the instrument in danger
zones (explosives zones)!
Wear eye protection for pressures > 1bar!
3 Operating
3.1 Switching on and off
Switching on Press the ON key (the maxi-
mum permissible measuring
range and the class appears
on the display).
For precision measurements
the instrument must be switched on for at least 1 minute
(warm-up phase).
Measuring negative differential or relative
pressures:
connect “S-”
or
change ports “S-“ and “+P”.
The HM28 will display a positive value.
3.3 Operating modes
The modes in the matrix below can be selected
in succession by pressing the MODE key.
After switching ON, the instrument is always
in the mode „normal“.
4
Î negative pressure,
When screwing on a coupling it
is important to hold with a spanner in the opposite direction.
Never hold at case only!
Switching on
Normal
(differential)
and
analogue/hold
Normal
(absolute)
and differential
Zoom
Min/Max
Leak rate
Tendency
(absolute)
Record 1)
Print Record
print
hold
print
print
print
print
print
start/stop
print
quick keystroke:
max. output speed
Keystroke
approx.1s:
single or fast
output start/stop
printing
zero
display
zero
diff
zero
display
zero
(reset)
zero
display
clear
memory
Display example
Max. Range:
200 mbar
Full scale error
0.05 %
123.45 mbar
====== or
HLD 123.4 mbar
1013.2 mbar
DIF 1013.2 mbar
123.45
MAX 150.0 mbar
MIN 100.0 mbar
1234.5 mbar
LEK 2.1 /min
1013.2 mbar
TND - 15.7 /min
REC 432.1 mbar
STOP 30 s MEM 1
REC 432.1 mbar
RUN 30 s MEM 321
432.1 mbar
STOP 30 s MEM 901
PRINT RECORD
PUSH PRINT
PRT 432.1 mbar
321 00:13:30
PRT
Record stopped
Notes
Measuring range
displayed in desired
unit
Accuracy class as a %
of full scale reading
Only with differential
or relative pressure
models
Hold, store indicated
value
Only with absolute
pressure mode Zero
sets Diff to 0
Measurement in large
figures
With absolute pressure,
reset to actual value
Only with Diff./Rel.
(unit/time unit)
Only with absolute
pressure (unit/time unit)
If measurement
memory cleared
Recording runs up to
964 values
Recording stopped
Appears only if values
are stored
Printing / display with
time
Recording stopped
1) at 70 bar the measurements are stored in [bar]
5
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