TSI Instruments HM675 User Manual

HM675 QUICK START GUIDE
Key Pad
Each key and its function are described below.
READ
Pressing the READ key initiates taking a time-averaged reading based on the current
setting of the time constant (TC).
UNITS GAUGE
Pressing the UNITS GAUGE key allows for toggling through the available units for gauge
pressure measurements (High P and Low P).
UNITS ΔP
Pressing the UNITS ∆P key allows for toggling through the available units for differential
pressure measurements (dP).
ZERO GAUGE
Pressing the ZERO GAUGE key initiates zeroing of the gauge pressure sensor.
TIME
CONSTANT
Pressing the TIME CONSTANT key allows for toggling through the available settings for
the time constant (TC) as follows: 1, 5, 10, 20, and 30 seconds.
CONTRAST 
Press the CONTRAST ▲ key to increase the display contrast.
CONTRAST 
Press the CONTRAST ▼ key to decrease the display contrast.
Press the key to turn the HM675 Hydronic Manometer on or off.
Press the BACKLIGHT key to turn the display’s backlighting on or off.
Instrument Power
The HM675 Hydronic Manometer can be powered by four (4) AA-size batteries (alkaline or rechargeable NiMH)
or the AC adapter.
Battery Installation
Locate the battery cover on the back of the unit and loosen the screw to remove. Take out the battery holder and
replace with fresh batteries (alkaline or rechargeable NiMH). Ensure that the batteries are correctly oriented within
the battery holder and Set the battery-type selection switch to indicate the type of batteries to be used (alkaline or
rechargeable NiMH). Reinstall the battery holder and battery cover.
Using the AC Adapter
The AC adapter allows the HM675 Hydronic Manometer to be powered from a standard AC wall outlet. When
using the AC adapter, alkaline batteries (if installed) will be bypassed. The AC adapter also charges the NiMH
type batteries (if installed) in the unit.
Zeroing the Gauge Pressure Sensor
With the (+) and (-) pressure ports open to atmosphere, and the valve handle on the manometer set to the
MEASURE position, press the ZERO GAUGE key.
Zeroing the Differential Pressure Sensor
Turn the valve handle on the manometer to the BYPASS position while in the main Measurement Screen to
automatically zero the differential pressure sensor. Zeroing of the differential pressure sensor occurs any time the
valve handle is turned to the BYPASS position. Any pressures applied to the hoses will not affect the dP zeroing
function and allows for zeroing of the differential pressure sensor while maintaining connections to the system
under test.

TSI Instruments HM675 Specifications

General

Brand	TSI Instruments
Model	HM675
Category	Measuring Instruments
Language	English

Summary

Instrument Power Options

Battery Installation Guide

Details on how to install batteries, including orientation and battery-type selection.

AC Adapter Usage

Explains powering the manometer via AC adapter and its effect on battery charging.

Zeroing Pressure Sensors

Gauge Pressure Sensor Zeroing

Procedure for zeroing the gauge pressure sensor with ports open to atmosphere.

Differential Pressure Sensor Zeroing

Method for zeroing the differential pressure sensor by turning the valve handle to BYPASS.

Hose Connections and Air Bleeding

Connecting Pressure Hoses

Instructions for connecting the red (high) and blue (low) pressure hoses to the manometer.

Bleeding Entrained Air

Step-by-step guide to remove air from the pressure hoses before measurement.

Pressure Measurement Types

Performing Pressure Measurements

Overview of simultaneous high-side and differential pressure measurement display.

Discrete Pressure Measurements

Taking a single time-averaged reading after pressing the READ key.

Performing Temperature Measurements

Using optional probes to measure temperature, linked to DP measurement units.