Alnor HM680, Owner'S Manual, Page: 17 / 40

Chapter 3. Getting Started 11
Flow
The flow reading is indicated as
Flow
on the manometer display. It represents a calculated value
determined from the measured Differential pressure and user entered values for the valve flow
coefficient (
Cv
or
Kv
) and fluid specific gravity.
Cv/Kv
The valve flow coefficient is indicated as
Cv (Kv)
on the manometer display. The
Cv (Kv)
value
may be edited within the Flow Measurement screen by using the ▲ and ▼ keys to highlight the
current setting, and the ◄ and ► keys to change its value.
Notes:
The
Cv (Kv)
value of the measured valve must be known in order to obtain meaningful flow
readings.
100 different
Cv (Kv)
names and values can be stored in the instrument (Reference
Chapter 4).
Making Temperature Measurements
The HM680 Hydronic Manometer accessory temperature probe is a 1/8” diameter, stainless steel sheathed
immersion probe designed for measurement of water line temperatures. When using the accessory
temperature probe, the HM680 Hydronic Manometer is equipped to make and display continuous
temperature measurements in both the Pressure and Flow Measurement screens.
Connecting the Temperature Probe
Connect the keyed 3-pin plug of the accessory temperature probe to the mating connector located on the
right-hand side of the manometer.
Notes:
A locking nut is provided on the accessory temperature probe plug to allow for a more secure
attachment when connecting to the manometer.
Setting Units of Measure
The units of measure for gauge pressure, differential pressure, flow, and temperature are adjusted within
either the Pressure or Flow Measurement screens by using the
▲ and ▼ keys to select the unit to change,
and the ◄ and ► keys to adjust to the desired unit setting. Available unit settings are as follows:
Gauge Pressure:
psi, inH
2
O, ftH
2
O, inHg, kPa, mH
2
O, mmHg, and bar
Differential Pressure:
psi, inH
2
O, ftH
2
O, inHg, kPa, mH
2
O, mmHg, and bar
Flow:
USGPM, UKGPM, m
3
/h, l/s, l/m
Temperature:
°
F or °C
Storing Discrete Measurements
Taking a discrete measurement allows for measurement, display, and storage of a single time-averaged
reading taken over the sampling period as defined by the current time constant setting. Discrete
measurement values are stored to the memory (current Test ID) and displayed on-screen for a period of
ten (10) seconds or until the
READ key has been pressed again.
1.
Press the READ key (from the Pressure or Flow Measurement screen).