Alnor HM680 User manual

HM680
Hydronic Manometer
OWNER’S MANUAL

LIMITATION OF WARRANTY AND LIABILITY
Copyright©
TSI Incorporated / February 2005 / All rights reserved.
Address
TSI Incorporated / Alnor Products / 500 Cardigan Road / Shoreview, MN 55126 / USA
Telephone No. Fax No.
[phone] [phone]
LIMITATION OF WARRANTY AND LIABILITY (effective July 2000)
Seller warrants the goods sold hereunder, under normal use and service as described in the operator's
manual, shall be free from defects in workmanship and material for twenty-four (24) months, or the length
of time specified in the operator's manual, from the date of shipment to the customer. This warranty
period is inclusive of any statutory warranty. This limited warranty is subject to the following exclusions:
a. Hot-wire or hot-film sensors used with research anemometers, and certain other components when
indicated in specifications, are warranted for 90 days from the date of shipment.
b. Parts repaired or replaced as a result of repair services are warranted to be free from defects in
workmanship and material, under normal use, for 90 days from the date of shipment.
c. Seller does not provide any warranty on finished goods manufactured by others or on any fuses,
batteries or other consumable materials. Only the original manufacturer's warranty applies.
d. Unless specifically authorized in a separate writing by Seller, Seller makes no warranty with respect
to, and shall have no liability in connection with, goods which are incorporated into other products or
equipment, or which are modified by any person other than Seller.
The foregoing is IN LIEU OF all other warranties and is subject to the LIMITATIONS stated herein. NO
OTHER EXPRESS OR IMPLIED WARRANTY OF FITNESS FOR PARTICULAR PURPOSE OR
MERCHANTABILITY IS MADE.
TO THE EXTENT PERMITTED BY LAW, THE EXCLUSIVE REMEDY OF THE USER OR BUYER, AND
THE LIMIT OF SELLER'S LIABILITY FOR ANY AND ALL LOSSES, INJURIES, OR DAMAGES
CONCERNING THE GOODS (INCLUDING CLAIMS BASED ON CONTRACT, NEGLIGENCE, TORT,
STRICT LIABILITY OR OTHERWISE) SHALL BE THE RETURN OF GOODS TO SELLER AND THE
REFUND OF THE PURCHASE PRICE, OR, AT THE OPTION OF SELLER, THE REPAIR OR
REPLACEMENT OF THE GOODS. IN NO EVENT SHALL SELLER BE LIABLE FOR ANY SPECIAL,
CONSEQUENTIAL OR INCIDENTAL DAMAGES. SELLER SHALL NOT BE RESPONSIBLE FOR
INSTALLATION, DISMANTLING OR REINSTALLATION COSTS OR CHARGES. No Action, regardless
of form, may be brought against Seller more than 12 months after a cause of action has accrued. The
goods returned under warranty to Seller's factory shall be at Buyer's risk of loss, and will be returned, if at
all, at Seller's risk of loss.
Buyer and all users are deemed to have accepted this LIMITATION OF WARRANTY AND LIABILITY,
which contains the complete and exclusive limited warranty of Seller. This LIMITATION OF WARRANTY
AND LIABILITY may not be amended, modified or its terms waived, except by writing signed by an Officer
of Seller.
Service Policy
Knowing that inoperative or defective instruments are as detrimental to TSI as they are to our customers,
our service policy is designed to give prompt attention to any problems. If any malfunction is discovered,
please contact your nearest sales office or representative, or call Customer Service at [phone] or
[phone].
.

i
CONTENTS
About This Manual..................................................................................................................... iii
Formatting and Typography....................................................................................................iii
Technical Assistance—Help! ..................................................................................................iii
Chapter 1. Safety.........................................................................................................................1
Safety Warnings......................................................................................................................1
Chapter 2. Introduction ..............................................................................................................3
Instrument Description............................................................................................................3
Unpacking...............................................................................................................................4
Chapter 3. Getting Started ......................................................................................................... 5
Keypad....................................................................................................................................5
Powering the Instrument.........................................................................................................6
Using the AC Adapter .......................................................................................................6
Installing the Batteries.......................................................................................................6
Instrument Start-up .................................................................................................................7
Zeroing the Manometer...........................................................................................................7
Zeroing the Gauge Pressure Sensor ................................................................................7
Zeroing the Differential Pressure Sensor..........................................................................8
Connecting the Manometer to the Test Points........................................................................8
Attaching the Hoses to the Manometer.............................................................................8
Bleeding the Entrained Air ................................................................................................8
Attaching the Hoses to the Test Points.............................................................................9
Making Pressure Measurements ............................................................................................9
Accessing the Pressure Measurement Screen.................................................................9
Pressure Measurement Screen ........................................................................................9
Continuous Measurements.............................................................................................10
Making Flow Measurements.................................................................................................10
Accessing the Flow Measurement Screen......................................................................10
Flow Measurement Screen .............................................................................................10
Making Temperature Measurements....................................................................................11
Connecting the Temperature Probe................................................................................11
Setting Units of Measure.......................................................................................................11
Storing Discrete Measurements............................................................................................11
Disconnecting the Manometer from the Test Points.............................................................12
Chapter 4. Main Menu............................................................................................................... 13
Zero Gauge Pressure............................................................................................................13
Select Cv/Kv Factor ..............................................................................................................13
Select Fluid ...........................................................................................................................13
Water...............................................................................................................................13
Other...............................................................................................................................13
Edit Current Cv/Kv Factor.....................................................................................................14
Set K Factors-Offsets............................................................................................................14
dP K Factor.....................................................................................................................14
Gauge K Factor...............................................................................................................14
Temperature Offset.........................................................................................................14
Set Date and Time................................................................................................................14

ii
Setup Instrument...................................................................................................................14
Decimal...........................................................................................................................14
Contrast...........................................................................................................................14
Beeper.............................................................................................................................14
Time Constant.................................................................................................................14
Auto Off...........................................................................................................................15
Chapter 5. Data Logging Menu ................................................................................................17
View Test ID Statistics ..........................................................................................................17
View Log Data.......................................................................................................................17
Choose Test ID.....................................................................................................................17
Edit Test ID Name.................................................................................................................18
Setup Logging.......................................................................................................................18
Delete Data...........................................................................................................................18
Delete a Sample..............................................................................................................18
Delete a Test ID..............................................................................................................18
Delete All Log Data.........................................................................................................18
Chapter 6. Calculations Menu.................................................................................................. 19
Brake Power..........................................................................................................................19
Heat Flow..............................................................................................................................20
Cv/Kv.....................................................................................................................................21
Pump Law Impeller Diameter................................................................................................22
Pump Law Delta P ................................................................................................................23
Pump Law Brake Power........................................................................................................24
Chapter 7. Maintenance and Troubleshooting....................................................................... 25
Routine Maintenance............................................................................................................25
Draining the Hoses..........................................................................................................25
Draining the Manometer Valve........................................................................................25
Cleaning the In-line Hose Filters.....................................................................................25
Cleaning the Instrument Housing....................................................................................26
Battery Charging...................................................................................................................26
Calibration.............................................................................................................................27
Troubleshooting ....................................................................................................................27
Chapter 8. USB Downloading to a Computer.........................................................................29
Installing the USB Software ..................................................................................................29
Connecting the Manometer to the Computer........................................................................29
First Time Connection.....................................................................................................29
Software Interface.................................................................................................................30
All TestIDs.......................................................................................................................31
Cv Factors.......................................................................................................................31
TestIDs Folder.................................................................................................................31
Downloading Data.................................................................................................................31
Specifications* .......................................................................................................................... 33

iii
About This Manual
This manual explains how to set up, operate and maintain the Alnor®HM680 Hydronic Manometer. Read
it thoroughly before using the instrument.
Formatting and Typography
Step-by-step instructions are numbered in boldface type: 1,2,3, etc., set flush-left against the
margin.
References to keys on the manometer and the instrument's displayed readout are represented by a
typeface called Arial. In addition to the different typeface, displayed messages appear in quotes.
Technical Assistance—Help!
For technical assistance or questions about the instrument or this manual, or if the HM680 Hydronic
Manometer needs repair or recalibration, call Technical Support at [phone] or [phone].

1
Chapter 1. Safety
Safety Warnings
Carefully read each of the following safety warnings prior to using the HM680 Hydronic
Manometer.
Never use the HM680 Hydronic Manometer or accessories on potable water systems or other systems
which may be used to convey fluids for human or animal consumption.
Never use the HM680 Hydronic Manometer to measure the pressure of volatile, flammable, or
otherwise hazardous fluids or gasses. The instrument is not designed to be intrinsically safe, nor is it
designed for use with caustic or corrosive chemicals.
Never connect the HM680 Hydronic Manometer or accessories to systems which exceed the
instrument’s maximum pressure specification (300 psi; 2068 kPa).
Observe proper safety precautions and wear appropriate personal protective equipment, including
gloves and eyewear, when working on high pressure or high temperature systems. Ruptured or
leaking lines pose a potential risk of serious personal injury.
When using the HM680 Hydronic Manometer, verify all hose connections are secure prior to taking
pressure measurements. Loose connections may result in the discharge of pressurized water or air,
posing a potential risk of serious personal injury.
Exercise caution when disconnecting the HM680 Hydronic Manometer from a pressurized system.
Water or air discharged under pressure poses a potential risk of serious personal injury.
Exercise caution in using the HM680 Hydronic Manometer near electrical equipment. Water spray
associated with purging or disconnecting hoses presents a potential risk of damage to such equipment.
Thoroughly drain and dry the HM680 Hydronic Manometer hoses and internal piping after each use.
This will help in limiting the potential for growth of hazardous microorganisms.

3
Chapter 2. Introduction
The HM680 Hydronic Manometer is an easy-to-use instrument designed for the accurate measurement of
pressure and calculation of flow in non-potable water and air systems. Features of the manometer include
the following:
Single-function keys for ease of use
Simultaneous measurement and display of High-side gauge and Differential pressure
Direct calculation and display of Low-side gauge pressure
Direct calculation and display of flow
Automatic density corrected readings
Data logging with calculated statistics
Output port for downloading stored data to a computer
User-selectable units of measure
User-selectable time constant
Easy-to-read, dot matrix LCD with backlight
Power supplied via AC adapter or batteries (alkaline or rechargeable NiMH)
Internal NiMH battery charging
Automatic power shutoff
Splash-proof case
Rugged carrying case for storage of meter, hoses, accessories, tools, and paperwork
6-inch temperature probe
Instrument Description
The HM680 Hydronic Manometer includes a meter, 6-inch temperature probe, hard carrying case,
(2) 6-foot (1.8 m) hoses with shut-off valves, (2) P/T gauge adapter probes, (2) B&G readout probes,
(2) ¼” Flare male × ¼” NPT male fittings, AC adapter, (4) NiMH batteries, external battery charger, neck
strap, owner’s manual, and NIST traceable certificate.
Figure 1: HM680 Meter Description
Keypad
Bottom Port Cover
A
C Power
A
dapter
Input Port USB Port
Dot Matrix
LCD Display
Pressure
Ports
Neck/Hanging
Strap Clips
Valve Handle
Temperature
Probe Port Temperature Port Cover

4 HM680 Hydronic Manometer
Unpacking
As you unpack the instrument and accessories, check the components against your packing list. If any
parts are missing or damaged, notify Alnor immediately. Tables 1 and 2 list standard and optional
components for the HM680 Hydronic Manometer.
Table 1: Standard Components
Item Part No.
6 in. (15 cm) long, 0.125 in. (3.175 mm) dia. Temperature probe 801291
Carrying case 1319409
Red hose assembly with shut-off valve 632650035
Blue hose assembly with shut-off valve 632650034
P/T gauge adapter probes (2) 632360004
B&G readout probes (2) 632360010
AC adapter 2182003
AA-size NiMH battery, four required 1208048
Battery holder 1801206
Neck strap 2913011
Owner’s manual 1980518
Pocket screw driver 3012054
External battery charger with (4) AA NiMH batteries (USA only) 801093
Table 2: Optional Components
Item Part No.
12 in.(30 cm) long, 0.125 in.(3.175 mm) dia. Temperature probe 801292
Accessory fittings kit HMFIT
Please complete the registration card included with this product and mail it promptly. Registration of the
product allows us notify you of product updates. If you prefer, you may register your HM680 through our
website at www.alnor.com.

5
Chapter 3. Getting Started
Keypad
Each key and its function is described below.
▲▼
The ▲and ▼keys are used to navigate through menus or to select an item to change. When entering
text, these keys change the highlighted letter/number.
◄►
The ◄and ►keys are used to change the selected item. When entering text, these keys are used to
index the cursor to the desired location.
ESC
The ESC key is used to return to the previous screen or to cancel an operation without saving
changes made to displayed information.
The ENTER key is used to select a menu item, or to accept changes made within a menu item and
return to the previous screen. From either the Pressure or Flow Measurement screens, pressing the
ENTER key accesses the Main Menu.
READ
Pressing the READ key initiates taking a time-averaged reading based on the current time constant
setting. After taking the reading, the values are stored to memory (current Test ID) and displayed on
screen for a period of ten (10) seconds or until the READ key has been pressed again.
Press the BACKLIGHT key to turn the display’s backlighting on or off.
Note: Backlighting has a significant impact on battery life. Use backlighting only when working in
areas where you cannot read the display with existing light.
DATA
Pressing the DATA key from either the Pressure or Flow Measurement screens provides access to the
Data Logging Menu.
PRESS
Pressing the PRESS key from the Flow Measurement screen provides access to the Pressure
Measurement screen.
ON/OFF
Press the ON/OFF key to turn the HM680 Hydronic Manometer on or off.
CALC
Pressing the CALC key from either the Pressure or Flow Measurement screens provides access to the
Calculations Menu.

6 HM680 Hydronic Manometer
FLOW
Pressing the FLOW key from the Pressure Measurement screen provides access to the Flow
Measurement screen.
Powering the Instrument
The HM680 Hydronic Manometer is equipped to be powered either by four (4) AA-size batteries
(alkaline or rechargeable NiMH) or the AC adapter.
Using the AC Adapter
The AC adapter allows the HM680 Hydronic Manometer to be powered from a standard AC wall outlet.
When using the AC adapter, the batteries (if installed) will be bypassed. The AC adapter also charges the
NiMH type batteries (if installed) in the unit.
Note: With the battery-type selection switch set to NiMH, the manometer will initiate charging the
batteries whenever the AC adapter is connected.
Installing the Batteries
To install/replace the batteries:
1. Turn the manometer off and locate the battery cover on the back of the unit.
2. Loosen the screw on the battery compartment cover and lift to remove.
3. Remove the battery holder. Tapping the backside of the meter against your hand may assist in
removing the battery holder.
4. Remove the old batteries and replace with fresh batteries (alkaline or rechargeable NiMH). Ensure
that the batteries are correctly oriented within the battery holder.
5. Set the battery-type selection switch to indicate the type of batteries to be used (alkaline or
rechargeable NiMH).
Figure 2: Location of Battery-Type Selection Switch
Battery Type
Selection Switch

Chapter 3. Getting Started 7
6. Reinstall the battery holder. Ensure the battery holder orientation is such that its terminals make
contact with the spring contacts within the battery compartment.
7. Replace the battery compartment cover.
Notes: The NiMH batteries included with the instrument may require recharging prior to first use.
Fully charged batteries should enable the instrument to operate for a period of at least twelve
(12) hours
Setting the battery-type selection switch properly will prevent unwanted charging of non-
rechargeable alkaline batteries and provide charging of NiMH batteries when the AC adapter is
connected.
A battery charge life remaining indicator is shown on the display whenever the manometer is
powered by batteries, and turned on.
When using NiMH batteries, the indicator of battery charge life remaining will not be accurate
due to their inherent non-linear voltage drop with power use.
Due to the danger of battery leakage, remove batteries from the battery compartment prior to
storage.
Never mix battery types.
For maximum battery life, ensure backlight is “off” when not needed.
Instrument Start-up
Upon turning the HM680 Hydronic Manometer on, the meter will engage in a brief self-check while
displaying the serial number, model number, and revision of the instrument being used. In completing the
self-check, the user is given the option to zero the gauge pressure sensor prior to proceeding to the
Pressure Measurement Screen.
Zeroing the Manometer
The HM680 Hydronic Manometer is equipped with both a gauge and differential pressure sensor,
allowing for simultaneous measurement and display of High-side gauge and Differential pressure. The
gauge and differential pressure sensors are zeroed independently of one another.
Zeroing the Gauge Pressure Sensor
To ensure the most accurate gauge pressure (High P) measurements, the HM680 gauge pressure sensor
should be zeroed prior to taking readings on each new system. When not in the instrument start-up
sequence, the gauge pressure sensor is zeroed as follows:
1. Enter the Main Menu.
2. Select Zero Gauge Pressure.
3. Follow the on-screen instruction to complete the gauge pressure sensor zeroing process.
Notes: Zeroing the gauge pressure sensor requires the user to disconnect the High pressure (red)
hose; as such it is often most convenient to zero the gauge pressure sensor as part of the
start-up sequence (i.e,. before hoses have been connected).

8 HM680 Hydronic Manometer
The zero offset of the gauge pressure sensor is sensitive to temperature changes. If moving
the manometer between areas of extreme temperature difference, it is best to allow the meter
to settle to the new temperature prior to zeroing.
Zeroing the Differential Pressure Sensor
To ensure the most accurate differential pressure (dP) measurements and calculated flow (Flow) values,
the HM680 differential pressure sensor should be zeroed prior to taking readings on each new system.
The differential pressure sensor is zeroed as follows:
1. Turn the valve handle on the manometer to the BYPASS position.
2. Follow the on-screen instruction to complete the differential pressure sensor zeroing process.
Notes: Zeroing of the differential pressure sensor is unaffected by pressures applied to the meter
during zeroing. This feature allows for successful zeroing of the differential pressure sensor
while maintaining connections to the system under test.
Zeroing of the differential pressure sensor is initiated any time the valve handle has been
turned to the BYPASS position while in the Pressure or Flow Measurement screens. This
feature allows for successful zeroing of the differential pressure sensor while entrained air is
being purged from the hoses.
The zero offset of the differential pressure sensor is sensitive to temperature changes. If
moving the manometer between areas with extreme temperature difference, it is best to allow
the meter to settle to the new temperature prior to zeroing.
Connecting the Manometer to the Test Points
Attaching the Hoses to the Manometer
1. Connect the straight female flare fitting on the High pressure (red) hose to the male fitting on the top
of the manometer marked with a plus (+) sign.
2. Connect the straight female flare fitting on the Low pressure (blue) hose to the male fitting on the top
of the manometer marked with a minus(-) sign.
Bleeding the Entrained Air
To ensure the most accurate pressure measurements, all entrained air within the hoses should be purged as
follows:
1. Turn the shut-off ball valve on both the High and Low pressure hoses to the closed position.
2. Turn the valve handle on the manometer to the MEASURE position.
3. Using an appropriate fitting, connect the open end of the High pressure (red) hose to the test point
with the higher line pressure.
4. Attach the appropriate fitting to the open end of the Low pressure (blue) hose.
5. Place the open end of the Low pressure (blue) hose in a suitable receptacle or near a drain.
6. Turn the shut-off ball valve on both the High and Low pressure hoses to the open position.
7. Turn the valve handle on the manometer to the BYPASS position to allow the liquid flow to displace
the entrained air.

Chapter 3. Getting Started 9
Note: Zeroing of the differential pressure sensor is initiated any time the valve handle has been
turned to the BYPASS position while in the Pressure or Flow Measurement screens. This
feature allows for successful zeroing of the differential pressure sensor while entrained air is
being purged from the hoses.
8. Once the liquid is flowing steadily from the Low pressure (blue) hose, turn the valve handle on the
manometer to the MEASURE position.
Attaching the Hoses to the Test Points
1. As indicated previously, use an appropriate fitting to connect the open end of the High pressure (red)
hose to the test point with the higher line pressure.
2. Using an appropriate fitting, connect the open end of the Low pressure (blue) hose to the test point
with the lower line pressure.
Note: If the hoses are connected in the inverse orientation (i.e. High pressure (red) hose to the
lower line pressure), the displayed High-side gauge pressure (High P) will be less than the
Low-side gauge pressure (Low P), and the Differential pressure (dP) and resulting
calculated flow (Flow) will be negative.
Making Pressure Measurements
The HM680 Hydronic Manometer allows for simultaneous measurement and display of the High-side
gauge and Differential pressure. The calculated Low-side gauge pressure is also displayed. While in the
Pressure Measurement screen, the manometer makes and displays continuous pressure measurements, and
allows for discrete data storage to the memory.
Accessing the Pressure Measurement Screen
The Pressure Measurement screen is accessed by pressing the PRESS key from the Flow Measurement
screen, or by pressing the ESC key from any of the primary menus (Main Menu, Data Logging Menu,
and Calculations Menu) when that menu was accessed from the Pressure Measurement screen.
Pressure Measurement Screen
*Shown with the accessory temperature probe attached.
Figure 3: Pressure Measurement Screen
High-Side Gauge
Pressure
Low-Side Gauge
Pressure
*Temperature
Differential
Pressure
Current Test ID Battery Status or
Power Input Type

10 HM680 Hydronic Manometer
High-Side Gauge Pressure
The High-side gauge pressure measurement is indicated as High P on the manometer display.
Low-Side Gauge Pressure
The Low-side gauge pressure reading is indicated as Low P on the manometer display. It represents a
calculated value determined from the measured High-side gauge and Differential pressure as follows:
Low P = High P - dP
Differential Pressure
The Differential pressure measurement is indicated as dP on the manometer display.
Continuous Measurements
The HM680 Hydronic Manometer makes and displays continuous pressure measurements whenever the
manometer is in the Pressure Measurement or Flow Measurement screen, with the exception of when the
READ key is pressed. The displayed readings are averaged measurements taken over the sampling period
as defined by the current time constant setting. The display is updated once per second.
Making Flow Measurements
The HM680 Hydronic Manometer allows for continuous calculation and display of flow. While in the
Flow Measurement screen, the manometer makes and displays continuous pressure measurements,
calculates and displays continuous flow readings, and allows for discrete data storage to the memory.
Note: The Cv (Kv) value of the measured valve must be known in order to obtain meaningful flow
readings.
Accessing the Flow Measurement Screen
The Flow Measurement screen is accessed by pressing the FLOW key from the Pressure Measurement
screen, or by pressing the ESC key from any of the primary menus (Main Menu, Data Logging Menu,
and Calculations Menu) when that menu was accessed from the Flow Measurement screen.
Flow Measurement Screen
*Shown with the accessory temperature probe disconnected.
Figure 4: Flow Measurement Screen
Current Cv (Kv)
factor name
*Temperature
Differential
Pressure
Flow
Current Test ID Battery Status or
Power Input Type
Current Cv (Kv)
factor value

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, inH2O, ftH2O, inHg, kPa, mH2O, mmHg, and bar
Differential Pressure: psi, inH2O, ftH2O, inHg, kPa, mH2O, mmHg, and bar
Flow: USGPM, UKGPM, m3/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).

12 HM680 Hydronic Manometer
2. Allow the manometer to stand undisturbed until the reading is complete (time of completion is
dependent on the time constant setting).
Note: Discrete measurements stored from the Pressure Measurement screen will not contain flow data.
Disconnecting the Manometer from the Test Points
Caution should be exercised when disconnecting the HM680 Hydronic Manometer from a pressurized
system, as water or air discharged under pressure poses the potential risk of serious personal injury. The
following provides a guideline for disconnecting the manometer from the test points once measurements
have been completed.
1. Turn the shut-off ball valve on both the High and Low pressure hoses to the closed position.
2. Disconnect the High pressure (red) hose from the higher line pressure test point.
3. Disconnect the Low pressure (blue) hose from the lower line pressure test point.
Note: If additional measurements at another location/system containing the same fluid are to be
made, it is not necessary to proceed to step 4 and drain the fluid entrained within the hoses at
this time. The fluid remaining within the hoses will help minimize the time necessary to bleed
entrained air prior to making subsequent measurements.
4. Place the open end of the Low pressure (blue) hose in a suitable receptacle or near a drain.
5. Turn the valve handle on the manometer to the BYPASS position.
6. Turn the shut-off ball valve on the Low pressure (blue) hose to the open position to discharge the
pressurized fluid out of the open end of the Low pressure (blue) hose.
7. Elevate the High pressure (red) hose and turn its shut-off ball valve to the open position to allow for
draining of the remaining entrained fluid.

13
Chapter 4. Main Menu
The Main Menu is accessed by pressing the ENTER key from either the Pressure or Flow Measurement
screens.
Figure 5: Main Menu
Zero Gauge Pressure
This Main Menu option allows for zeroing the manometer’s gauge pressure sensor.
Select Cv/Kv Factor
This Main Menu option allows for selecting any of the 100 user-programmed valve flow coefficients (Cv
or Kv) stored within the instrument. The most recent selected Cv (Kv) factor will be the default when
entering the Flow Measurement screen.
Select Fluid
This Main Menu option allows for setting the fluid type (Water or Other) of the system being measured.
Defining the fluid type is necessary in order for the manometer to account for the fluid’s specific gravity
when calculating flow.
Water
In selecting Water, the instrument will automatically determine the specific gravity based upon the
measured temperature of the fluid (Tprobe).
Note: If the accessory temperature probe is not connected, the user will have the option of manually
entering the fluid temperature (T-entered).
Other
In selecting Other, the manometer will prompt the user to enter the fluid’s specific gravity.
Note: When Other is selected as the fluid type, the entered value for specific gravity will not be
compensated with changes in temperature.

14 HM680 Hydronic Manometer
Edit Current Cv/Kv Factor
This Main Menu option allows for editing the type (Cv or Kv), name (up to 9 characters), and value of
the current selected Cv (Kv) factor.
Set K Factors-Offsets
This Main Menu option allows for defining a K-factor (multiplier) or offset to adjust the baseline factory
calibration curve for the differential pressure sensor, gauge pressure sensor, or accessory temperature
probe.
dP K Factor
A K factor for differential pressure measurements is selectable from 0.800 to 1.200. The default is 1.000.
Gauge K Factor
A K factor for gauge pressure measurements is selectable from 0.800 to 1.200. The default is 1.000.
Temperature Offset
An offset value for temperature probe measurements is selectable between ± 5.4 °F (± 3.0 °C).
Set Date and Time
This Main Menu option allows for adjustment and setting of the instrument real-time clock.
Setup Instrument
This Main Menu option allows for defining the following parameters:
Decimal
This setting adjusts the format of the delimiter in both displayed and stored data. The available decimal
settings are PERIOD and COMMA.
Contrast
This setting adjusts the contrast of the manometer display.
Beeper
This setting adjusts whether or not keypad presses are accompanied by an audible beep. The available
beeper settings are ON and OFF.
Time Constant
This setting adjusts the current value of the time constant. The available settings for the time constant are:
1, 5, 10, 20, and 30 seconds.