Decagon Devices VP-4 Operator's Manual

Operator’s Manual

Decagon Devices, Inc.

Version: July 10, 2017 — 12:32:13

VP-4

Decagon Devices, Inc.

2365 NE Hopkins Court

Pullman WA 99163

Phone: [phone]

Fax: [phone]

Website: www.decagon.com

Email: [e-mail] or [e-mail]

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2017 Decagon Devices, Inc.

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VP-4 CONTENTS

Contents

1 Introduction 1

1.1 Customer Support . . . . . . . . . . . . . . . . . . . . 1

1.2 Warranty . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.3 Seller’s Liability . . . . . . . . . . . . . . . . . . . . . . 2

2 About VP-4 3

2.1 Specifications . . . . . . . . . . . . . . . . . . . . . . . 3

3 Theory 8

4 RH Sensor 10

4.1 RH Sensor Conditioning . . . . . . . . . . . . . . . . . 11

5 Connecting Sensors 12

5.1 Connecting to an Em50 Series Logger . . . . . . . . . 12

5.2 Connecting to a Non-Decagon Logger . . . . . . . . . 13

5.3 Pigtail End Wiring . . . . . . . . . . . . . . . . . . . . 13

6 Communication 15

6.1 Digital Communication for Data Logger . . . . . . . . 15

7 Installation 18

8 Troubleshooting 20

9 References 21

10 Declaration of Conformity 22

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VP-4 1 INTRODUCTION

1 Introduction

1.1 Customer Support

If you ever need assistance with your VP-4, or if you just have ques­tions or feedback, there are several ways to contact us. Customer ser­vice representatives are available to speak with you Monday through
Friday, between 7am and 5pm Pacific time.

Note: If you purchased your VP-4 through a distributor, please con­tact them for assistance.

Email:
[e-mail] or [e-mail]

Phone:
509-332-5600

Fax:
509-332-5158

If contacting us by email or fax, please include as part of your mes­sage your instrument serial number, your name, address, phone, fax
number, and a description of your problem or question.

Please read these instructions before operating your sensor to en­sure that it performs to its full potential.

1.2 Warranty

The sensor has a 30-day satisfaction guarantee and a one-year war­ranty on parts and labor. Your warranty automatically validates
upon receipt of the instrument.

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1 INTRODUCTION VP-4

1.3 Seller’s Liability

Seller warrants new equipment of its own manufacture against de­fective workmanship and materials for a period of one year from the
date of receipt of equipment.

Note: We do not consider the results of ordinary wear and tear,
neglect, misuse, accident as defects.

The Seller’s liability for defective parts shall in no event exceed the
furnishing of replacement parts “freight on board” the factory where
originally manufactured. Material and equipment covered hereby
which is not manufactured by Seller shall be covered only by the
warranty of its manufacturer. Seller shall not be liable to Buyer for
loss, damage or injuries to persons (including death), or to property
or things of whatsoever kind (including, but not without limitation,
loss of anticipated profits), occasioned by or arising out of the instal­lation, operation, use, misuse, nonuse, repair, or replacement of said
material and equipment, or out of the use of any method or process
for which the same may be employed. The use of this equipment con­stitutes Buyer’s acceptance of the terms set forth in this warranty.
There are no understandings, representations, or warranties of any
kind, express, implied, statutory or otherwise (including, but with­out limitation, the implied warranties of merchantability and fitness
for a particular purpose), not expressly set forth herein.

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VP-4 2 ABOUT VP-4

2 About VP-4

The VP-4 measures air temperature, relative humidity (RH), vapor
pressure, and barometric pressure. A microprocessor within the VP­4 calculates vapor pressure from the RH and temperature measure­ments. The VP-4 uses a sensor chip to measure both air temperature
and RH and a secondary chip to measure barometric pressure. Each
VP-4 has calibrations coefficients stored on board. The calibration
coefficients are applied before data are output. Air temperature, rel­ative humidity, vapor pressure, and barometric pressure are output
from the sensor using an RS232 (TTL) string and the common SDI­12 communication protocol.

The VP-4 sensor is packaged in a rugged Delrin housing with the
sensor electronics potted in marine grade polyurethane encapsulant.
The RH/T sensor chip is protected by a hydrophobic porous Teflon
filter that is water and dust proof, but has an extremely high vapor
conductance allowing fast sensor equilibration with the surrounding
atmosphere. An additional stainless steel screen protects the Teflon
filter and RH/T sensor from impact and abrasion. The rugged design
allows the VP-4 to withstand long term exposure to hostile condi­tions, making it ideal for a wide range of applications including stan­dard meteorological monitoring, evapotranspiration measurement,
greenhouse monitoring and control, concrete moisture monitoring,
and building humidity monitoring for mold prevention and remedia­tion.

2.1 Specifications

Relative Humidity

Range: 0 to 100% RH

Resolution: 0.1% RH

Accuracy: Sensor measurement accuracy is variable across a range

of RH. Refer to the chart in Figure 1 to determine the accuracy
specification for the VP-4 sensor:

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2 ABOUT VP-4 VP-4

Equilibration Time (τ, 63%): <40 s (response time in 1 m/s air

stream)

Hysteresis: <1% RH typical

Long term Drift: <0.5% RH/year typical

Figure 1: Humidity Accuracy Chart

Temperature

Range: −40◦C to 80◦C

Resolution: 0.1◦C

Accuracy: Sensor measurement accuracy is variable across a range

of temperatures. Refer to the chart in Figure 2 to determine
the accuracy specification for the VP-4 sensor:

Equilibration Time (τ, 63%): < 400 s (response time in 1 m/s air

stream)

Long term drift: < 0.04◦C/year typical

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VP-4 2 ABOUT VP-4

Figure 2: Temperature Accuracy Chart

Vapor Pressure

Range: 0 to 47 kPa

Resolution: 0.001 kPa

Accuracy: Sensor measurement accuracy is variable across a range

of temperatures and RH. Refer to the chart below to determine
the accuracy specification for the VP-4 sensor:

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