Download
Share
Print this page
Alpha Moisture Systems CMH-DM-RPC Instruction Manual
  1. Manuals
  2. Brands
  3. Alpha Moisture Systems Manuals
  4. Measuring Instruments
  5. CMH-DM-RPC
  6. Instruction manual

Alpha Moisture Systems CMH-DM-RPC Instruction Manual

Chilled mirror dew point hygrometer
Hide thumbs

Advertisement

Quick Links

Download this manual
Model CMH-DM-RPC
Chilled Mirror Dew Point Hygrometer
Instruc
on Manual
English

Advertisement

loading
Need help?

Need help?

Do you have a question about the CMH-DM-RPC and is the answer not in the manual?

Questions and answers

Subscribe to Our Youtube Channel

Related Manuals for Alpha Moisture Systems CMH-DM-RPC

Summary of Contents for Alpha Moisture Systems CMH-DM-RPC

  • Page 1 Model CMH-DM-RPC Chilled Mirror Dew Point Hygrometer Instruc on Manual English...

  • Page 2: Safety Informa On

    fica Warnings Risk of electric shock - Do not open any part of the enclosures of the CMH-DM-RPC or any electrical apparatus whilst connected to the mains supply. Do not connect the CMH-DM-RPC or any electrical apparatus to the mains supply un...
  • Page 3 Model CMH-DM-RPC before use. This manual should be kept with the Model CMH-DM-RPC for future reference. You must also observe the safety informa on on pages 15 and 37 before installa Please read this manual carefully from the start.
  • Page 4 Model CMH-DM-RPC Index Introduc Model CMH-DM-RPC Func onal Descrip General Overview Chilled Mirror Model CMH Cooling Unit – RPC Temperature Controller Temperature Controller Factory Default Se West Instruc on (1) West Instruc on (2) MIrror Bala Programmable Func The ABC Cycle...

  • Page 5: Table Of Contents

    Model CMH-DM-RPC Serial Output External Device Connec PC or Terminal Setup RS-232 Commands and Parameter Se General Help Menu Help Menu Table Start an ABC Cycle ABC Enable ABC Start Time ABC Internal ABC Analog Hold ALARM 1 AND (OPTIONAL) ALARM 2...
  • Page 6 Model CMH-DM-RPC Introduc Thank you for purchasing an Alpha Moisture Systems Model CMH-DM-RPC We are sure that you will agree that the CMH-DM-RPC is easy and friendly to use, reliable and accurate. At Alpha Moisture Systems we are commi ed to customer sa...
  • Page 7 Model CMH-DM-RPC Func onal Descrip General Overview The CMH-DM-RPC Instrument is designed to measure gas moisture as low as –90°C dewpoint. It comprises a standard Alpha Moisture Systems CMH three stage pel er cooled mirror hygrometer which gives a 95°C temperature depression across the pel er ba ery at 25°C with...

  • Page 8: Temperature Controller

    Model CMH-DM-RPC Temperature Controller The temperature controller is mounted on the front panel of the auxiliary cooling module. Its opera on is fully automa c and does not need to be adjusted. A ‘T’ type thermocouple is mounted in the wall between the pel...
  • Page 9 Model CMH-DM-RPC Temperature Controller Factory Default Se 1) Configura on Mode - Unlock Code 20 Parameter Value Note: If any values are Input Range/Type changed then the AUTO/MAN key must be pressed a Scale Range Upper Limit 50.0 each change to accept the Scale Range Lower Limit -50.0...
  • Page 12 Alpha Moisture Systems chilled mirror hygrometers, because the compensa circuit and the low thermal mass of the Sensor design permit the use of a heavy condensate layer on the mirror surface without the need for a coalescence pre-cool cycle or other gimmicks to offset...
  • Page 13 Model CMH-DM-RPC Programmable Func ons Con nued Isolated 4-20mA Output: An isolated 4-20mA op on is available for applica ons requiring complete isola on between the Model CMH and the 4-20 ma output. As with the standard 4-20mA output, the range matches the 0-5V output set on the Model CMH. Maximum loop...
  • Page 14 Model CMH-DM-RPC Specifica Dew/Frost Point Range -90°C to +20°C Accuracy Dew point/Frost ±0.2°C Dew/Frost Point 3-wire Pla num Resistance Thermometer (PRT) Temperature Sensor 100 ohms at 0°C, nominal Depression S3 Sensor - 95°C, nominal at 25°C Auxiliary Coolant Fan cooled, refrigerant condensing unit with temperature controller .
  • Page 15 Model CMH-DM-RPC Outputs Track or Hold Outputs (analogue, digital, alarms) can be set to Track or Hold while in Auto Balance or Programming mode. (Factory default is HOLD) Voltage (Standard) 0 to 5 VDC, scalable from –100 to 20°C (-148 to 68°F), 1KΩ minimum...
  • Page 16 (Please Recycle Packaging). Locate and keep the small box containing the Cleaner Kit. Heavy Item The CMH-DM-RPC is a heavy instrument weighing approx 40kg. We strongly recommend a minimum of two fit and capable people to li the item into its permanent posi on.
  • Page 17 Model CMH-DM-RPC Sample Connec A basic requirement of accurate dewpoint measurements is the proper design of the gas sampling system. In order that the Model CMH measures the actual moisture content of the gas, it is essen al that the sampling components neither contribute to, nor absorb moisture from the gas.
  • Page 18 A sintered stainless steel filter is normally suitable Available from Alpha Moisture Systems. The filter will form a hygroscopic element that will contribute some lag to the sample system. In the design of hygrometer sample systems, minimise the number of components, such as valves, tees, and filters, upstream of the Sensor .
  • Page 19 Model CMH-DM-RPC Selec on Of Components At Low Dew Points Rubber, neoprene, tygon and most plas c tubing are unsuitable for use in hygrometer systems as sample lines from the sample point to the Sensor . Non-hygroscopic tubing, such as stainless steel, Teflon, or KEL-F with a minimum of joints and fi...

  • Page 20: Bottom Row

    Model CMH-DM-RPC Informa on Display Func The Informa on Display Informa on Displayed THE LARGE LCD Display mounted on the Front Panel provides the user with all the informa necessary to properly operate the DM. It can be used as the primary interface with the...
  • Page 21 Model CMH-DM-RPC Opera ng the Dew Master In order to operate this instrument, it is assumed that you have read the INSTALLATION sec on of this manual, and preliminary tasks have been done. These include: 1. The instrument has been connected to a proper AC power source.
  • Page 22 Model CMH-DM-RPC Informa on display in detail - Con nued Real me informa on is displayed in the upper le corner of the main Informa on Display window. This is programmable via the keypad. It is in non-vola le memory with ba...
  • Page 23 Model CMH-DM-RPC Programming the Dew Master Keypad Opera The DM front panel keypad in Table 3-1 has six “so keys” that support the user set up and opera- on. The label for each key, and it’s func on are described below.
  • Page 24 Model CMH-DM-RPC Scroll Menu (Using the Arrow Keys) The SCROLL MENU facilitates access to DISPLAY Setup, ANALOG Setup, ALARM Setup, ABC Setup, and SERIAL Setup. In the SCROLL MENU, use the UP , DOWN, LEFT and RIGHT arrows to make your selec on and then press the ENT key.
  • Page 25 Model CMH-DM-RPC Analogue Output Analog Output 1 is located on the rear panel. The SCROLL MENU is used to assign parameters to the analog output channel. The analog output (OUT1) is also scaled by selec ng the low (LO) and high (HI) range.

  • Page 26: Serial Output

    Model CMH-DM-RPC Programming the Serial Port Serial Output The RS232-C serial port is located on the rear panel. To access serial communica on it is necessary to have the Serial Enable on (ON), from the SCROLL MENU, and also to select the appropriate baud rate.

  • Page 27: Help Menu Table

    Model CMH-DM-RPC Help Menu Table Commands Examples (Max Entries Shown) Start a Manual ABC Cycle AB <CR> ABC enable toggle AE <CR> ABC Start Time (HH:MM) AS <CR> 23:59 <CR> Analog Hold Toggle (on/off) AH <CR> ABC Interval (HH:MM) AI <CR> 23:59 <CR>...

  • Page 28: Abc Start Time

    Model CMH-DM-RPC ABC Start Time Type the le ers “AS” and press the ENTER key. Enter the me “Hours:Minutes” in 24 hr . format, and press the ENTER key. Examples: “02:00”, is 2:00 AM: “14:30” is 2:30 PM. ABC Internal Type the le ers “AI”...

  • Page 29: Alarm 1 And Alarm 2 Latches

    Model CMH-DM-RPC Alarm 1 and Alarm 2 Latches The alarms can be set to latch on an alarm condi on by typing "L1" for alarm 1 or "L2" for alarm 2. A latched alarm will not reset itself when the alarm condi...

  • Page 30: Poll For Output

    Model CMH-DM-RPC Poll for Output This command requests the DewMaster to send serial data at any me and is independent of the automa c interval. Type the le er “P” and press the “ENTER” key. Manual Heat This command toggles the Sensor’s heater on or off. It can be ini...

  • Page 31: Dewmaster System Status Report

    Model CMH-DM-RPC DewMaster System Status Report ABC data: State StartTime Interval Hold ENABLED 0:00:00 2:00 ALARM data: Item Type Value Latch State HIGH 0.00 C READY -5.00 C ACTIVATED ANALOG data: Item High -20.00 C 40.00 C -40.00 C 60.00 C...

  • Page 32: Help Menu Table

    Model CMH-DM-RPC Help Menu Table. Example (Max Entries Shown) Display the HELP Menu <CR> Enter New Time (HH:MM:SS) <CR> 23:59:59 Enter New Date (MM:DD:YY) <CR> 12:31:99 Temperature Unit (F ,C) <CR> C <CR> ABC Start Time (HH:MM) <CR> 23:59 <CR>...

  • Page 33: Baud Rate

    Model CMH-DM-RPC Baud Rate The available baud rates in the CMH are: 19200, 9600, 4800, 2400, 1200, or 300 NOTE: Both the Model CMH and the computer must be set to the same baud rate for communi- on to take place. If the unit is not communica...

  • Page 34: Default Programmable Parameters

    Model CMH-DM-RPC Default Programmable Parameters If a fault is detected in the parameter memory, or if the non-vola le memory chip is replaced, the instrument will replace all of the user entered parameters with the default parameters listed in Table 3-5.

  • Page 35: Temperature

    Model CMH-DM-RPC System Opera on - Con nued The Model CMH Dewpoint Hygrometer accurately measures the dewpoint of a gas by cooling a mirrored surface, over which the gas flows un l a layer of dew forms on the surface.

  • Page 36: Circuit Descrip Ons

    Model CMH-DM-RPC Circuit Descrip Thermoelectric Dewpoint Temperature Control Circuit The thermoelectric dewpoint temperature control circuit heats and cools the mirror surface of the dewpoint sensor to the temperature at which a layer of dew on the mirror is in equilibrium with the moisture in the sample gas in the Sensor .

  • Page 37: Alarm Set

    Model CMH-DM-RPC Automa c Mirror Balance Control Circuits - Con nued The dura on of the hea ng period is pre-programme. At low temperatures more me is needed to evaporate the condensate. If the temperature at the beginning of the ABC cycle is greater than 0°C, the mirror is heated for 1 minute, between 0°C and –25°C, 2 minutes and below –25°C the...

  • Page 38: Mirror Cleaning Schedule

    Model CMH-DM-RPC Mirror Cleaning Schedule Contrary to what might be expected, the mirror surface in the Sensor need not be spotless for proper opera on. In fact, mirror surface contaminants can act as nuclei for the condensate, thus hastening dew forma The build-up of contamina on on the mirror surface normally occurs very slowly.

  • Page 39: Calibra On Of Prt

    Model CMH-DM-RPC Mirror Cleaning - Con nued er cleaning the mirror surface, remove all traces of the cleaning fluid with the dry end of the cot- ton bud. To remove par culate ma er present around the mirror surface, use a clean, dry co bud, not isopropyl alcohol.

  • Page 40: Opera Ng Adjustments

    Model CMH-DM-RPC Repeat steps 6,7, and 8 as o en as required to bring each reading to within ±0.1°C of the values given. Each adjustment interacts slightly with the others so it may be necessary to repeat these steps several mes.

  • Page 41: Compensa On

    Model CMH-DM-RPC Gain - Con nued The GAIN control is set at the factory to give stable opera on over the range of opera on of the instrument. Before making adjustments to the GAIN control, always record the factory-set posi to aid in returning to the original posi on at a later date.

  • Page 42: Suggested Spares

    Model CMH-DM-RPC Suggested Spares We recommend that instruments be returned to the factory for repairs or replacement of parts. Some users may, however, be capable of making repairs in the field. In these cases, spare parts that may be needed in infrequent circumstances may include.
  • Page 43 Model CMH-DM-RPC Trouble Shoo ng - Con nued Symptom Correc ve Ac CONTROL indicator is too far le This indica on can occur if the Sensor is not plugged in, if the or too far right during the Sensor has been changed, or if the Sensor mirror surface is the ABC indicator is on steady.
  • Page 44 Model CMH-DM-RPC Symptom Recommended checks and replacement Not all three power supply volt- This is probably caused by a failure in one of the power sup- ages, +5V, +15V, and –15V, are plies or a poor cable connec on from the transformer to the present.

  • Page 45: Test Points

    Model CMH-DM-RPC Test Points The following test points are available on the main PC board: The summing point of the main servo amplifier . Output of servo amplifier . This voltage ul mately controls the Sensor current and is also the voltage represented by the CONTROL LEDs.

  • Page 46: Contact Informa On

    96 City Road Bradford West Yorkshire BD8 8ES United Kingdom Tel: +44 (0) 1274 733 100 Email: info@amsystems.co.uk Website: amsystems.co.uk Office opening hours: Monday - Thursday 8.30am - 5.30pm GMT Friday 8.30am - 5.00pm Notes: © Alpha Moisture Systems Ltd.