Delta-T Devices AP4 User Manual
  1. Manuals
  2. Brands
  3. Delta-T Devices Manuals
  4. Measuring Instruments
  5. AP4
  6. User manual

Delta-T Devices AP4 User Manual

Porometer
Hide thumbs
Table of Contents

Advertisement

Quick Links

Download this manual
User Manual for the
AP4 Porometer
Version 4
Version 4.0
Delta-T Devices

Advertisement

Table of Contents
loading
Need help?

Need help?

Do you have a question about the AP4 and is the answer not in the manual?

Questions and answers

Related Manuals for Delta-T Devices AP4

Summary of Contents for Delta-T Devices AP4

  • Page 1 User Manual for the AP4 Porometer Version 4 Version 4.0 Delta-T Devices...

  • Page 2: Copyright

    Copyright Copyright © 2019 Delta-T Devices Ltd User Manual version 4 First published: 1991 AP4 Design team : Chris Nicholl : Project leader and software Tom Bragg : Electronic hardware John Wood : Theory, head design & testing Edmund Potter : Testing &...

  • Page 3: Table Of Contents

    YOURSELF Error! Bookmark not defined. YOUR ENVIRONMENT Unpacking YOU SHOULD HAVE OPTIONAL ACCESSORIES YOU WILL ALSO NEED How to Use the AP4 SETTING UP AND SHUTTING DOWN SETTING UP A TYPICAL MEASUREMENT SESSION MEASURMENTS WITH ONE HAND CALIBRATION PREPARATION WETTING THE FILTER PAD...
  • Page 4 CYCLE SETTINGS SCREEN READINGS CYCLE FLOW CHART STORE READINGS STORE READINGS FLOW CHART REVIEW OUTPUT TO COMPUTER REQUIREMENTS Run AP4 Retrieve on your PC TYPICAL PRINT OUT OF DATA Planning Your Experiment CHECKS HOW MANY READINGS TO TAKE MEMORY USAGE EXAMPLE PLAN...
  • Page 5 Contents THE LIGHT SENSOR CLEANING THE SENSOR HEAD DESICCANT Layout and Control CONTROL KEYS MENU NAVIGATION FLOWCHART Specifications SENSOR HEAD CONTROL UNIT CABLES DATA COLLECTION SOFTWARE OPERATING LIMITS CALIBRATION PLATE VALUES At 20°C, 1000 hPa PERFORMANCE SPECIFICATIONS (cont'd) CE CONFORMITY Warranty, Service, Technical Support Terms and Conditions of Sale Service, Repairs and Spares...

  • Page 6: Introduction

    Introduction Introduction The AP4 cycling porometer is used for measuring the stomatal resistance of plant leaves. This is a measure of the resistance to loss of water vapour through the stomata and is an indicator of the physiological state of the plant. Stomata are sensitive to light, carbon dioxide, pollutants, water stress and pathogens.

  • Page 7: Warnings

    AVOID CONTAMINATING THE CALIBRATION PLATE AVOID WARMING THE HEAD OR CALIBRATION PLATE BY EXCESSIVE HANDLING OR EXPOSURE TO THERMAL RADIATION DO NOT LEAVE A LEAF OR THE CALIBRATION PLATE IN THE HEAD WHEN THE AP4 IS NOT CYCLING WHOLE INSTRUMENT...

  • Page 8: Unpacking

    (At 2019, AP4 Retrieve v1.1 works on Windows XP, Vista, Windows 7, Windows 8 and Windows 10) • Access to a PC for AP4 Retrieve and to a PC or other device for browsing and/or printing the AP4 Technical Manual.pdf. •...

  • Page 9: How To Use The Ap4

    • Charge battery. Recharge battery every year or more frequently if storing above 20°C. See Battery Care and Service: page 11 of the AP4 Technical Manual. • Protect from dust, humidity greater than 80%, smoke organic solvent fumes and sulphurous pollutants.

  • Page 10: A Typical Measurement Session

    EXIT to return to the main menu. REVIEW the data OUTPUT the data to a PC running AP4 Retrieve See also Calibration: page 12 Measurements with one hand: page 11 How to Read: Page 25 Planning your experiment: page 39...

  • Page 11: Measurments With One Hand

    A TYPICAL MEASUREMENT SESSION MEASURMENTS WITH ONE HAND The AP4 permits one-handed operation. Be sure to start each measurement session with a calibration. TO TAKE A READING with one hand MAIN MENU: Turn AP4 on Press GO READ CALIBRATE REVIEW OUTPUT...

  • Page 12: Calibration

    10 % error in measured resistance. If the pressure does not change significantly between calibration and measurement, then you can get away without a barometer. See Pressure on page 31. See page 8 in the AP4 Technical Manual (download at www.delta-t.co.uk) Page 12...

  • Page 13: Wetting The Filter Pad

    CALIBRATION WETTING THE FILTER PAD Wet the paper all over with distilled water. Remove the excess water with blotting paper or absorbent tissue paper. Repeat two more times with fresh dry absorbent paper. Page 13...

  • Page 14: Stick Down The Pad

    CALIBRATION STICK DOWN THE PAD Place the damp filter paper on the back of the calibration plate to cover all the calibration holes. Seal down with sticky tape. Trim loose tape from the edges. Smooth down the tape to remove any air pockets. Return the calibration plate to its plastic zipper-lock bag until needed.

  • Page 15: Calibration Loop

    CALIBRATION CALIBRATION LOOP There are three stages: Insert Plate, Calibration cycle and Install. The program will lead you through the measurement of all six positions before asking you whether to install the new calibration. It automatically keeps track of where you are. Calibration Flow Chart MAIN MENU: WAITING...
  • Page 16 CALIBRATION Page 16...

  • Page 17: Insert Plate Screen

    Cup type Slotted or circular cups can be chosen. See Cup: How to Change it – page 17 in AP4 Technical Manual * Order: Choose whether to go from calibration plate position 1 to 6 or from 6 to 1 Units: s.cm...

  • Page 18: Calibrate Settings

    CALIBRATION * Download the AP4 Technical Manual at www.delta-t.co.uk CALIBRATE SETTINGS mbar EFFECT OF ALTITUDE ON 1000 AVERAGE BAROMETRIC PRESSURE 5000 m ALTITUDE ALTITUDE TYPICAL 1030 EFFECT OF UK WEATHER mbar BAROMETRIC PRESSURE TIME (HOURS) Page 18...

  • Page 19: Calibration Cycle

    CALIBRATION CALIBRATION CYCLE The porometer is automatically cycling and taking measurements of the transit time. This is the time it takes the calibration plate to release enough moisture to raise the cup RH by a fixed amount. Dry air is then pumped through the chamber until the RH is a few percent below the set point.

  • Page 20: Insert Plate (For Subsequent Plate Positions)

    CALIBRATION (for subsequent plate positions) INSERT PLATE After choosing ACCEPT in the first calibration cycle run you automatically return to the INSERT PLATE screen. The reading you have just accepted is displayed in the results column. It will have been automatically converted from time to resistance or conductance units. You may also notice the corresponding true calibration plate value updated in the righthand column.
  • Page 21 CALIBRATION Page 21...

  • Page 22: Install Calibration

    CALIBRATION INSTALL CALIBRATION After you select FIT CURVE the AP4 accepts the last reading at the last plate position, and with the readings from all the other positions, it calculates the new calibration constants for the cup. The new calibration is then used to recalculate the measured values in the left-hand results column.

  • Page 23: Install Calibration Flow Chart

    CALIBRATION INSTALL CALIBRATION FLOW CHART Page 23...

  • Page 24: Calibration Summary

    CALIBRATION CALIBRATION SUMMARY • Prepare calibration plate ahead of time. • Leave it to stabilize, in its plastic envelope, for about 1 hour. • Set RH close to ambient. • Check other settings: - Cup type: slotted or circular Units: resistance or conductance Pressure: actual barometric pressure or average barometric pressure at your altitude or leave it at 1000 hPa (mbar) •...

  • Page 25: How To Read

    HOW TO READ HOW TO READ This section describes how to take readings by driving the porometer around the READ loop, and what settings can be changed. WARNINGS • Keep cup relative humidity (RH) below 80% if possible. • Avoid exposing the cup to organic solvents and smoke. •...
  • Page 26 HOW TO READ Readings Flow Chart TO TAKE A READING with one hand MAIN MENU: Turn AP4 on Press GO READ CALIBRATE REVIEW OUTPUT INSERT lEAF Insert leaf Press GO START Wait 4 or 5 cycles until readings are READING CYCLE steady or until Beep Beep sounds 1 2.3...

  • Page 27: Settings

    HOW TO READ SETTINGS There are checks and settings to think about if you want to be accurate. You also have choices, such as what units you want the results displayed in and what titles to use for groups of data. Setting the communications protocol with computer is a choice you must get right.
  • Page 28 HOW TO READ PATH ITEM OPTIONS Output title 0 - 16 characters READ/INSERT LEAF/SET "Plant" name 0 - 5 characters "Leaf" name 0 - 5 characters READ/READINGS CYCLE/SET Beeping On/Off And also CALIBRATE /CALIBRATION Units cm.s-1 CYCLE/SET mm.s-1 m2.s.mol-1 s.cm-1 s.m-1 mmol.m-2 s-1 CALIBRATE/ INSERT...

  • Page 29: Insert Leaf Screen Display

    HOW TO READ INSERT LEAF SCREEN DISPLAY The left-hand box on the display refers to what has changed since the AP4 was last recalibrated. When one or more of the items flash it is time to recalibrate. "RH :" shows the difference between the current set point and that used at the last calibration.
  • Page 30 HOW TO READ Page 30...

  • Page 31: Reading Cycle

    Recalibrate if you change altitude by 1000 m or more, or if there is an extreme change of weather. See also Barometric Pressure on page 8 of the AP4 Technical Manual and How Results are Calculated, page 32 of the AP4 Technical Manual.

  • Page 32: Readings Cycle Flow Chart

    HOW TO READ READINGS CYCLE FLOW CHART Page 32...

  • Page 33: Store Readings

    If you want to you can label your plants with these numbers. You can label and read your plants in any order you like. Your AP4 just prints the number along with the rest of the data for that leaf. You do not have to start at number 1.

  • Page 34: Store Readings Flow Chart

    HOW TO READ STORE READINGS FLOW CHART Page 34...

  • Page 35: Review

    REVIEW REVIEW No editing can be done, and no settings changed within REVIEW. Page 35...

  • Page 36: Output To Computer

    You can also delete data using the OUTPUT, DISCARD option REQUIREMENTS The PC program AP4 Retrieve is used to download data to a PC . Before installing it on you PC please check latest installation requirements in the document AP4 Retrieve Release Notes at https://www.delta-t.co.uk/software/ap4-...
  • Page 37 OUTPUT TO COMPUTER AP4s are shipped with valid RS232 parameters set. These RS232 parameters should also work OK The data now copied to your PC Page 37...

  • Page 38: Typical Print Out Of Data

    OUTPUT TO COMPUTER TYPICAL PRINT OUT OF DATA Page 38...

  • Page 39: Planning Your Experiment

    Distilled water Cup shape Sensor Slotted or round Select Tech. Manual page 17 * head * In the AP4 Technical Manual Are you ready? Check that you know the following: • How to calibrate, and when. • How to record and output the data.

  • Page 40: How Many Readings To Take

    HOW MANY READINGS TO TAKE • Contact a statistician, or get a good statistics book, for advice on how to ensure your results are statistically significant. HOW MANY READINGS TO TAKE You can take nearly 1600 readings with no annotations added. This reduces to 632 if you add a 30-character note to each.

  • Page 41: How To Calculate Available Memory

    (32000 – (16 �� 44) Maximum number of readings 20 + 30 = 625 readings = 1 reading every 46 seconds for 8 hours In normal use the AP4 should be able to cope with 1 days' data with no problem. Page 41...

  • Page 42: Hints And Tips

    It is not bomb-proof however and will not necessarily save the AP4 if you drop it! Keep the zip fasteners done up. They hold the AP4's lid shut and help to reduce the ingress of dirt and dust.

  • Page 43: Choice Of Cup

    You will probably see the cup-leaf δT moving, and you should wait until it stabilises. The AP4 automatically compensates for non-isothermal conditions, but the correction will be inaccurate if the measured δT is lagging behind the true value.

  • Page 44: Sensitive Stomata

    As far as possible therefore, keep the sensor head shaded and the shutter over the leaf- pad closed. If the δT can be kept <1°C, you are doing well. The AP4 software will be applying its automatic correction anyway, and can cope with up to ±2.5°C. You may occasionally have to tolerate a higher δT though.

  • Page 45: Cup Temperature

    The AP4 automatically corrects for deviations of the cup temperature from the temperature of the calibration run. Above a 5°C shift the AP4 will start to flag a warning by flashing. The correction is good, i.e. remains within specification, to +10°C and - 5°C.

  • Page 46: Desiccant

    A 500 g pot of 2-5 mm beads of orange to green self-indicating silica gel is currently supplied with each AP4. The amount used in the AP4 silica gel tube is about 16 g so the pot may supply about 30 refills, if you store the pot in a dry place and close the lid immediately after use.

  • Page 47: Layout And Control

    Layout and Control Layout and Control Examine the head unit. It is like a large clothes peg, for clipping onto leaves. Identify the shiny mirrored surface of the RH sensor inside the cup. It is quite fragile and is also easily damaged by organic solvents.
  • Page 48 ● an input socket with a red light for the battery charger, ● and an RS232C serial interface socket for sending data to a printer or computer. TO TAKE A READING with one hand MAIN MENU: Turn AP4 on Press GO READ CALIBRATE REVIEW OUTPUT INSERT lEAF...
  • Page 49 Layout and Control Page 49...

  • Page 50: Control Keys

    Warnings: Page 7 Setting up and shutting down : Page 9 Battery care and recharging : Page 11 in the AP4 Technical Manual HELP HELP The HELP key provides context-sensitive information on what to do next. Up to 7 screens of help may be provided.
  • Page 51 Layout and Control The GO key is duplicated, for left and right-handed people, on both sides of the lid. The larger button on the porometer head is also a GO key. It is an action key, causing the execution of the selected or default menu option. Examples : ACCEPT a menu option DO a suggested command...
  • Page 52 Beginners can ignore this. Use this when replacing the AP4 head. It gives access to the “Configure AP4 Head Screen” Use it to install the appropriate calibration for a new light sensor and to zero the electronics circuit which measures the...
  • Page 53 OUTPUT CLOCK SETTINGS Date: 8/2/90 Format: mth/day/yr After Time: 12:34 Format: 24 hour Menu flowchart: AP4 Quick Start Settings options: page 27 ________________________________________________________________________ PLUS KEY MINUS KEY Example : The plus and minus key are used to change default settings.

  • Page 54: Menu Navigation Flowchart

    Layout and Control MENU NAVIGATION FLOWCHART Page 54...

  • Page 55: Specifications

    Specifications Specifications SENSOR HEAD Size: 110 x 30 x 27 mm Weight : 130 g (including cable) Cup apertures: 2.5 x 17.5 mm (slot with rounded ends) 6.0 mm dia (circular) Cable length: 1.1 m RH sensor IST P14 Rapid Temperature Betatherm 100K (curve 6) microchip thermistors sensors:...

  • Page 56: Cables

    USB to RS232 adapter DATA COLLECTION SOFTWARE Filename: AP4 Retrieve Function: Collects data from AP4 and saves to a file on a PC. Comma separated values (CSV) and ASCII text File format: Computer: A PC running Windows XP, Vista, Windows 7, Windows 8 or Windows 10.

  • Page 57: Calibration Plate Values At 20°C, 1000 Hpa

    Specifications CALIBRATION PLATE VALUES At 20°C, 1000 hPa Resistance Conductance Plate position s/cm s /m m2.s/mol cm/s mm/s mmol/m 27.3 2730 66.51 0.04 0.37 16.5 1650 40.02 0.06 0.61 18.03 0.14 1.35 7.55 0.32 3.23 3.90 0.63 6.25 1.95 1.25 12.50 Page 57...

  • Page 58: Performance Specifications (Cont'd)

    Specifications PERFORMANCE SPECIFICATIONS (cont'd) Test Conditions Resolution Accuracy Parameter Reading range note [1] note [2] Reading Range [5] >90 % 5- 800 mmol m Conductance 5.0 -1200 mmol m 0.1 - 10 >80 % 800 - 1200 mmol m >90 % 0.25 - 20 mm s Conductance 0.25 - 30.0 mm s...

  • Page 59: Ce Conformity

    Specifications CE CONFORMITY The Porometer type AP4 conforms to EC regulations regarding electromagnetic emissions and susceptibility when used according to the instructions contained within this user manual, and is CE marked by Delta-T Devices Ltd. Page 59...

  • Page 60: Warranty, Service, Technical Support

    Warranty, Service, Technical Support Warranty, Service, Technical Support Terms and Conditions of Sale Our Conditions of Sale (ref: COND: 1/07) set out Delta-T's legal obligations on these matters. The following paragraphs summarise Delta T's position but reference should always be made to the exact terms of our Conditions of Sale, which will prevail over the following explanation.

  • Page 61: Service, Repairs And Spares

    In your enquiry, always quote instrument serial numbers, software version numbers, and the approximate date and source of purchase where these are relevant. Contact details: Tech Support Team Delta-T Devices Ltd 130 Low Road, Burwell, Cambridge CB25 0EJ, UK email: tech.support@delta-t.co.uk email: repairs@delta-t.co.uk...

  • Page 62: Index

    43 andshake, 28 Cup apertures, 55 AP4 head cup temperature, 31 replacing, 52 Cup type, 28 AP4 Retrieve, 8, 36, 56 CYCLE SETTINGS, 19 arometer, 8 Data bits, 28 barometer, 12, 31 Date, 27 battery, 25 Date format, 27...
  • Page 63 Index INSERT PLATE, 17, 18, 20, 28 warnings, 25 Introduction, 6 Repairs, 61 keyboard, 48 Resistance labels, 29 units, 31 Layout, 48 Resolution, 58 Leaf, 27 RH "Set" value, 29 leaf number, 29 RH cycle level, 58 light sensor, 33, 47 RH sensor, 47, 55 orientation, 45 RH set point, 24, 25...
  • Page 64 Index temperature difference Hints and Tips, 42 leaf - cup, 31 large error in calibration curve fit, 22 Temperature sensors, 55 reading too slow, 20 Terms and Conditions of Sale, 60 thermistor damage, 22 Test Conditions, 58 variable readings, 44 thermistor, 47 units, 55 Thermistor, 28...

Table of Contents