Edgetech PPM1, PPM2 Operator's Manual

Model PPM1 & PPM2

Trace Moisture Analyzer

OPERATORS MANUAL

19 Brigham Street ● Unit #8 ● Marlborough, MA USA 01752

Tel. [508] 263-5900 ● [800] 276-3729 ● Fax [508] 486-9348

E-mail [e-mail] ● www.edgetechinstruments.com

Tel. [508] 263-5900 ● Fax [508] 486-9348

Rev. A June 2010

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PPM1 / PPM2

QUICK STARTUP GUIDE

STARTUP

PPM1:

1. Remove the cover, and mount the PPM1 in an easily visible position.

2. See Wiring Diagram in Installation, Section 4.

3. Wire Sensor connections.

4. Wire Power connections. Do not turn on Power at this time.

5. Wire two Analog (4 to 20 mA) Outputs if required.

6. Wire two Alarm Relays if required.

7. Wire and plug in the RS-232 connector if required.

8. Replace the outer cover. Do not over-tighten the screws.

9. Connect Sensor to dry gas source. Allow system time to dry out.

10. Turn on the Power Supply. Specifications are:
18 to 30 Vdc, unregulated, 100 mA max.

11. After the self-test procedure, start viewing or recording valid data.

PPM2:

1. Fully charge the rechargeable battery before operating.

2. Connect Sensor to dry gas source. Allow system time to dry out.

3. After the self-test procedure, start viewing valid data.

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TABLE OF CONTENTS Page

1.0 Quick Startup Guide 2

2.0 Commitment to Quality 5

3.0 Introduction 6

3.1 General Description 6

3.2 Technical Description 6

3.2.1 The PPM1/PPM2 System 6

3.2.2 The Phosphorous Pentoxide Sensor 6

3.2.3 Standard Factory Ranges 8

3.2.4 Gases to Avoid 9

4.0 Installation 9

4.1 Placement of Instrument 9

4.2 Mounting 9

4.2.1 Wall Mounting the Display 9

4.2.2 Sensor Mounting and Sampling 9

4.3 Electrical Wiring 10

4.3.1 Sensor Connections 10

4.3.2 Power Connections 10

4.3.3 Analog Outputs 10

4.3.4 Alarm Relays 10

4.3.5 RS-232 Serial Port 10

5.0 Operation

5.1 Startup 12

5.1.1 Dry Down Phase 1 12

5.1.2 Dry Down Phase 2 12

5.2 Measuring Dry Gases 13

5.2.1 Measurement Time 13

5.2.2 Materials 13

5.3 Operating the Instruments 13

5.3.1 The PPM1 13

5.3.2 The PPM2 13

5.4 Using the RS-232 Port for Programming 14

5.4.1 Serial Port Setup 14

5.4.2 Changing the Digital Display 14

5.4.3 Changing the Analog Outputs 15

5.4.4 Programming the Alarm Relays 17

5.4.5 Calibrating the Analog Outputs 20

5.4.6 Modifying the RS-232 Parameters 21

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6.0 Maintenance 23

6.1 General 23

6.1.1 Filters 23

6.1.2 Battery Maintenance 23

6.2 Gases 23

7.0 Specifications 24

8.0 Appendix 26

8.1 PPM1 Mounting Dimensions 26

8.2 Sensor Dimensions 27

8.3 Warranty 28

8.4 Notes 29

8.5 Basic Humidity Definitions 30

LIST OF ILLUSTRATIONS

3-1 Phosphorous Pentoxide Sensor 7
3-2 PPM1 Wall Mounted 7
3-3 PPM2 Portable 8
4-1 Wiring Connections 11

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2.0 EDGETECH'S COMMITMENT TO QUALITY

To Our Customers:

Thank you for purchasing one of our products. At EdgeTech, it is our
policy to provide cost-effective products and support services that
meet or exceed you requirements, to deliver them on time, and to
continuously look for ways to improve both. We all take great pride in
the products we manufacture.

We want you to be entirely satisfied with your instrument. The
information contained in this manual will get you started. It tells you
what you need to get your equipment up and running, and introduces
its many features.

We always enjoy hearing from the people who use our products. Your
experience with our products is an invaluable source of information
that we can use to continuously improve what we manufacture. We
encourage you to contact or visit us to discuss any issues whatsoever
that relate to our products or your application.

The Employees of EdgeTech

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3.0 INTRODUCTION

3.1 GENERAL DESCRIPTION

The PPM1 is a trace moisture analyzer designed specifically for monitoring low
levels of moisture, and reading them out in units of dew point and parts-per­million. This trace moisture analyzer utilizes an electro-chemical (P2O5) sensor in
combination with a proprietary semi-permeable diffusion membrane. The
principal of operation applies the Faraday’s Law of Electrolysis. It is a
fundamental measurement of the moisture present. The PPM1 is ideally used
in relatively clean, dry, inert gas applications. It is provided in a wall-mount
configuration. See Figure 3-2.

The PPM2 is a portable, battery operated version of the PPM1. It is provided in a
carrying case, with two gel-cell rechargeable batteries built in. See Figure 3-3.

3.2 TECHNICAL DESCRIPTION

3.2.1 THE PPM1/PPM2 SYSTEM

The gas passing through the phosphorous pentoxide cell results in a small
electrical current proportional to the quantity of water molecules (moisture) in the
sample. The small electrical current from the cell is conditioned so that it directly
corresponds to the concentration of moisture in the measured gas. This linear
output signal is available to actuate the programmable Alarm Relays, and also
provides information to the Digital Display and Analog Outputs. A
microprocessor controls all data processing and input and output functions of the
Instrument, ensuring a high accuracy measurement of moisture. Two separate
humidity parameters may be monitored and displayed.

3.2.2 THE PHOSPHOROUS PENTOXIDE (P2O5) MOISTURE SENSOR

The Sensor utilizes an electrochemical (phosphorous pentoxide - P2O5 - coated)
sensor in combination with a proprietary semipermeable diffusion membrane.
This membrane allows the water vapor molecules to pass from the dry gas
stream into the sensor cavity at a rate that is a function of the partial pressure of
the water across the membrane. It also allows the hydrogen and oxygen
molecules, the byproducts of the electrolysis, to diffuse back into the gas stream.

The membrane “meters” the gas flowing into the sensor cavity, ELIMINATING

THE NEED FOR PRESSURE REGULATION AND CONSTANT FLOW, which
are required in most other electrolytic hygrometers.

The phosphorous pentoxide moisture sensor, also called an electrolytic cell, has
the ability to measure trace quantities of water vapor in a dry gas. Operation is
based on the fact that if a small dc voltage is applied, water vapor molecules can
be electrolyzed into their elements of hydrogen and oxygen. To electrolyze each
water molecule, it is known that two electrons are required. Therefore, the

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quantity of current used by
the cell is proportional to
the number of water
molecules being
electrolyzed. If the dc
excitation current is
measured, water vapor
content of the gas can be
displayed. This
measurement process
provides a fundamental
measurement of water
vapor. While in a typical
electrolytic cell the rate of
gas flow must be carefully Figure 3-1 The Phosphorous Pentoxide
controlled by the user for (P2O5) Moisture Sensor
accurate measurements,
this cell is independent of
gas flow rate. Although a fundamental measurement technique normally does
not require calibration, each cell is calibrated at the Factory before shipment to
the user to compensate for variations in the diffusion membranes. Figure 3-1
shows the moisture sensor.

Figure 3-2 The PPM1 with Wall Mount housing and Moisture Sensor

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Figure 3-3 The PPM2 Portable Trace Moisture Analyzer

Figure 3-2 shows the wall mounted PPM1, and Figure 3-3 shows the portable
battery-operated PPM2.

3.2.3 STANDARD FACTORY RANGES

As received from the Factory, the instrument is programmed for the following
standard conditions. These may be field modified by the user by using the RS­232 serial port. See the Operation section for complete programming
information.

Digital Display Units: Set for ppmv and Dew Point
Analog Output Ranges: Set for 0 to 1250 ppmv, and -100°C to 0°C Dew Point
Alarm Relays Switching: Actuated at 100 ppmv, and -50°C Dew Point
RS-232 Port Update Rate: 5 seconds

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3.2.4 GASES TO AVOID

Caution: This instrument should not be used with gases that are corrosive or that
readily combine with phosphorous pentoxide to form water. GASES AND

MATERIALS THAT SHOULD BE AVOIDED INCLUDE CERTAIN ACIDS,
ALCOHOLS, CHLORINE, FLUORINE, HYDROGEN CHLORIDE, HYDROGEN
FLUORIDE, AMINES, AMMONIA, ALKYNES, ALKADIENES, AND ALKENES.

4.0 INSTALLATION

4.1 PLACEMENT OF INSTRUMENT

If possible, locate the PPM1 in a clean area. Choose a location where the
display may be conveniently observed. Depending on the location selected, it
may be convenient to wire the instrument prior to mounting.

4.2 MOUNTING

4.2.1 WALL MOUNTING THE DISPLAY

The plastic wall mount housing is mounted to a flat surface as follows:

1. Remove the front cover. Using a flat screwdriver, carefully unscrew the
four slotted plastic screws.

2. Mounting screws (not provided) are inserted in the same holes as the
cover screws. They must have a head diameter that is small enough
to fit inside the clearance holes, but large enough to press against the
collar located at the bottom of the holes. No. 8 pan head or round
head screws are recommended. See the wall mounting hole pattern in
the Appendix of this manual.

3. Reinstall the front cover. Do not over-tighten the cover mounting
screws.

4.2.2 SENSOR MOUNTING AND SAMPLING SYSTEM

The P2O5 Moisture Sensor is designed to measure very small quantities of Water
Vapor in the presence of other gases. It is manufactured of carefully selected
non-hygroscopic materials such as stainless steel. The use of more porous
materials such as plastic in your measuring system is strongly discouraged. In
order to obtain correct readings and acceptable response times, the sensor
sampling system must be carefully planned. Here are some recommendations:

 Tubing should be clean stainless steel, not plastic.
 If gas is brought from a long distance, use larger diameter tubing for faster

response time. Reduce diameter at the sensor fitting.

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