Retrotec DM32 Operation Manual Download Page 1

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Pressure Gauge Operation Manual

For Model DM32

rev-2017-04-24

Summary of Contents for DM32

Page 1: ...Pressure Gauge Operation Manual For Model DM32 rev 2017 04 24 ...

Page 2: ...Page 2 of 91 Retrotec 2017 Made by Retrotec 1060 East Pole Road Everson WA USA 98247 For support Call 1 888 330 1345 in USA 1 360 738 9835 outside USA support retrotec com or Fax 1 360 647 7724 ...

Page 3: ...d in accordance with the instructions may cause harmful interference to radio communications However there is no guarantee that interference will not occur in a particular installation If this equipment does cause harmful interference to radio or television reception which can be determined by turning the equipment off and on the user is encouraged to try to correct the interference by one or more...

Page 4: ...ding 16 2 6 2 Channel B Pressure Reading or Result 16 2 6 3 Set the Range Device connected to the gauge 17 2 6 4 Estimate Results with Pressure 19 2 6 5 Setting n value for Pressure extrapolation 19 2 6 6 Capture and apply a Baseline using Settings 20 2 7 Gauge compensates for sensor drift with Auto Zero 20 3 Get Results directly from the gauge 21 3 1 Connect Speed Control Cable between the gauge ...

Page 5: ...ect multiple gauges to a computer via Wired network 46 5 4 Connect computer or phone to the DM32 WiFi Hotspot 48 5 5 Make the DM32 join an existing WiFi network 50 5 5 1 Set secure wireless credentials using DM32 Configurator software 51 5 5 2 On DM32 verify wireless credentials after updating 51 6 Update gauge with new features 53 6 1 Connect the gauge to a computer via USB 53 7 Verify your gauge...

Page 6: ...e the effects of a constant wind 64 8 15 5 In extreme cases you can use a Wind Damping Kit designed to reduce wind related fluctuations 65 9 Technical Specifications 67 Appendix A Understanding Pressures on the Gauge 68 Differential Pressure 68 Positive vs Negative Pressure 68 Why static and fluctuating pressures occur causing bias 69 Managing fluctuating pressures created by wind 69 Reduce uncert...

Page 7: ...Page 7 of 91 Retrotec 2017 Glossary 89 ...

Page 8: ... gauge or return to an authorized service facility for examination and or repair Do not run cord under carpeting Do not cover cord with throw rugs runners or similar coverings Do not route cord under furniture or appliances Arrange cord away from traffic and where it will not be tripped over Do not place this equipment or power cord in water or other liquid Use only the included power plug to char...

Page 9: ...es a Data Logger Virtual Gauge for remote control and the DM32 Configurator DM32 gauge internal software can be updated with new features as they get developed from time to time using the DM32 Configurator software and the USB connection on the DM32 WiFi enabled gauges also include the GaugeRemote App for Android and iOS based smart phones and devices The gauge will conveniently control the speed ...

Page 10: ...stems is yellow Pressure tube ports on the top of the gauge are color coded to distinguish where pressure tubes are connected Retrotec has a specially designed pressure tube port that grips pressure tubes well but releases them without tearing after long term use This exclusive connector is designed by Retrotec to make contact with the both tube internally and externally with a shallow taper Figur...

Page 11: ...ch or a router in order to control fan and or read the gauge measurements via the computer 2 USB cable port Connect the USB A Micro B cable to a PC or the supplied AC power adapter in order to charge the internal battery of the gauge Connect the USB to a computer to update the software internal to the gauge firmware 3 Reset Press a paper clip into the hole to reset the gauge forces the gauge to tu...

Page 12: ...anywhere on the screen or until the gauge self check sequence finishes and automatically displays the Home screen Information displayed on the Splash Screen during start up includes Internal gauge software Firmware Build and Version Number Gauge Serial Number Upon gauge start up the Home screen will display the Device Range and Result to be displayed settings that were set on the gauge before it w...

Page 13: ...of 91 Retrotec 2017 Figure 7 Home screen keys when the gauge is idle not controlling a fan Figure 8 Home screen keys when gauge is seeking a target pressure 2 5 Observe icons on Top Bar to monitor gauge status ...

Page 14: ...n place of the Time Averaging value to indicate Channel A and Channel B display values are frozen to the values that were present when the display was tapped Figure 10 Tapping Channel A display area will HOLD the Result 2 5 4 Is the gauge connected to a Network The wired network icon appears when the network Status is set to Wired Settings Network Status Set Wired when an Ethernet cable is connect...

Page 15: ...DM32 is connected to power When the battery is charging a red light on the front of the gauge bottom right corner will be on solidly not flashing Once the light goes off the gauge is fully charged Additionally the battery life indicator on the Top Bar will be blue when the battery is being charged and the gauge is powered on With the gauge plugged into the wall outlet the battery charges at 1A and...

Page 16: ...e blue pressure port The Channel A Reading is also a key when it is tapped the Channel A and Channel B displays are frozen This feature is convenient for jotting down test data HOLD will be displayed in the Top Bar to indicate the readings have been frozen 2 6 2 Channel B Pressure Reading or Result The Channel B display can show the pressure difference between the yellow pressure port ref B and th...

Page 17: ...isplays correct results Table 4 List of devices compatible with the DM32 Device Manufacturer Device displayed Description Retrotec 200 Model 200 fan DucTester 1000 Model 1000 systems with 0 75 hp yellow wheel rim style fans 2000 Model Q46 and Q56 systems with 0 75 hp yellow foam core fan Same curves as 1000 3000 Older Model Q4E Q5E and QMG systems with 2 hp yellow foam core Door Fan Same curves as...

Page 18: ...ng the gauge and Fan Speed Control Adapter part FN275 produced by Retrotec Table 5 Images of devices compatible with the gauge 200 1000 yellow tube only 2000 yellow tube only 3000 yellow tube only 3000SR yellow and green tube MN DB MN 3 4 Exhaust Fan Flow Meter ...

Page 19: ...ates the Channel B Result to the Default Pressure set in the Settings screen using the n value chosen in Settings If the Set Pressure function is used Pressure extrapolates the Channel B Result to the pressure entered for Set Pressure using the n value chosen in Settings The Pressure function provides unique advantages over non extrapolated results There is no need to achieve an exact Channel A pr...

Page 20: ... to capture a Baseline Once captured the gauge will automatically subtract the Baseline pressure from all subsequently measured pressure readings and will display only the adjusted pressures on the screen The gauge averages Baseline pressure for a user defined duration Tip A 30 second Baseline acquisition is typically enough to establish an accurate baseline measurement If the building conditions ...

Page 21: ...se If the Range Configurations associated with the Device in use do not appear tap Change Device to change the Device first Tap Settings to display gauge settings that can be changed If the Area or Volume key appears tap to enter a value for conditioned area or volume which will be used to compute the result displayed on Channel B Tap Set Speed to run the fan at a particular speed Tap Set Pressure...

Page 22: ... 15 Set gauge speed control output Fans manufactured by TEC such as the DuctBlaster or Minneapolis Model 3 or 4 can also be controlled if an optional Retrotec TEC speed control Adapter is connected between the gauge and the TEC fan in the Speed Control cable as shown in Figure 12 Pressure tubing needs to be attached to the gauge using the Retrotec conventions described in the Retrotec literature 3...

Page 23: ...utput based on the pressure reading on Channel A Retrotec fans can be controlled directly from the gauge Figure 17 Set gauge to achieve target pressure Fans manufactured by TEC can also be controlled if the optional Retrotec TEC speed control Adapter is connected between the gauge and the TEC fan as shown in Figure 12 Pressure tubing needs to be attached to the gauge using the Retrotec conventions...

Page 24: ...ility results requiring an input of area for the calculation is selected as the Result to be displayed on Channel B Figure 19 Enter an Area if the Result to be displayed is calculated with an Area The Area key from the Home screen opens the same screen as the Settings Area key combination The Volume key only appears on the Home screen if ACH Air Changes per hour is selected as the Result to be dis...

Page 25: ...a key so by tapping here the results can be frozen at the value in place when the key is tapped called Hold When active you will see Hold displayed and flashing in the Top Bar Hold allows the user to copy results down without them changing and flashing Changing the Result is even available when display is frozen using HOLD Figure 21 HOLD Result on display by tapping Channel A To remove HOLD and re...

Page 26: ... Tap Channel B or Settings to change Result or units to be displayed Channel B acts as a key so by tapping it you can change the Result to be displayed at Channel B The Result to be displayed can also be changed by tapping on Settings Figure 23 Change Result to be displayed during operation ...

Page 27: ...le results for one fan speed setting Changing the Result is even available when display is frozen using HOLD Figure 24 Tap Channel B to change Result being displayed Each of the available results can be displayed with the user s choice of units Figure 25 Change Flow result units from CFM to cu m h 3 3 10 Tap Pressure to estimate Result at a different pressure ...

Page 28: ...ting pressure the extrapolation pressure will be exactly the target pressure If setting target pressure to zero then the gauge does not allow pressure extrapolation to be used For mathematical details on Pressure extrapolation see Appendix D For practical information on extrapolation see 2 6 4 Figure 26 Turn Pressure on Figure 27 Pressure is not available when Pressure is the Result on Channel B F...

Page 29: ...29 Pressure extrapolates to the target pressure when a pressure is set Figure 30 Jogging pressure while using Pressure changes target and pressure label If Set Speed function is used Tapping Pressure so that it is On extrapolates the Channel B Result to the Default Pressure using the n value both set in the second Settings screen ...

Page 30: ... Pressure when a speed is set Tapping Pressure so that it is Off will turn extrapolation off Tapping STOP will also turn extrapolation off and make it unavailable as long as HOLD is not being used to freeze the Result display Figure 32 Turn Pressure off leaves fan running ...

Page 31: ...Page 31 of 91 Retrotec 2017 Figure 33 Stopping fan disables and turns Pressure off ...

Page 32: ...or Result extrapolation when Set Speed is used select the inactivity time 15 min 30 min 1 h 2h Off after which the gauge powers itself down Power down time The gauge will not power itself down if Off is chosen enable or disable Sound feedback upon key press set an appropriate n value a slope for result extrapolation with Ducts 0 6 House 0 65 update gauge firmware by tapping Firmware Update Firmwar...

Page 33: ...ne 4 2 Set Area if using a Result per Area Dimensions are required for the gauge to calculate some of the results that are available to be displayed on Channel B The area is required for the calculation of any of the results that are divided by an area normalized leakage area and permeability results When required the Area key appears on the Home screen ...

Page 34: ...on the Home screen but allows the user to enter the area without changing the Result to be displayed to one of the normalized or permeability results to make the Home screen Area key appear Figure 38 Set the Area needed for per Area type Results from Settings 4 3 Set Volume if using ACH The volume of the enclosure or building under test is required for the calculation of ACH Air Changes per Hour T...

Page 35: ...ithout changing the Result to be displayed to ACH to make the Home screen Volume key appear 4 4 Use metric units for dimensions The gauge determines if the user prefers entry of the dimensions using metric or imperial units based on the choice of units for Flow or permeability results If the Result to be displayed is Flow in CFM or any of the permeability results with imperial units then the dimen...

Page 36: ...n Flow or other Result using area Figure 42 Set Volume using metric units when other Results are displayed in metric units 4 5 Set the Default Pressure If the Set Speed function is used and Pressure is On the Default Pressure that is chosen with this Setting will be the reference pressure for the Result displayed on Channel B that is extrapolated and displayed see section 3 3 10 ...

Page 37: ...Page 37 of 91 Retrotec 2017 Figure 43 Set the default pressure to be used as extrapolation pressure during set speed operation ...

Page 38: ...ging period Time averaging of 1s 5s 10s 30s can be selected directly or another value for time averaging in seconds can be entered manually For details on time averaging see section 2 5 2 Figure 44 Change time averaging depending on wind conditions ...

Page 39: ...re readings All pressure result displays are converted to the chosen pressure units including the Baseline and Default Pressure Figure 45 Choose units of Pressure to display Pa psf in WC 2 Tap any other Result to select it for display on Channel B The Result to be displayed can also be changed by tapping the Channel B display on the Home screen See section 3 3 9 ...

Page 40: ...change Result being displayed 3 Tap the selected Result continuously to cycle through different units available for the Result Figure 47 Change Result units For details on Pressure extrapolation to display the Result a particular pressure see section 2 6 4 ...

Page 41: ...the gauge If WiFi is enabled on your DM32 you will also see choices for WiFi Create to turn on the WiFi hotspot for phones and computers to find WiFi Join to let the DM32 join an existing network For information about using the gauge with a Network and for detailed instructions about further settings required refer to Section 5 The Status should be set as Disabled if the gauge will be connected to...

Page 42: ...ructions see Retrotec s Manual Software DM32 Configurator 4 10 Re calibrate the touchscreen The re calibration process resets the internal mapping of the touchscreen to physical areas on the screen Re calibration thus ensures the correct functions will be activated when a user touches the screen in the area of the keys Each display varies slightly so the touch screen is calibrated at the factory b...

Page 43: ...ou cannot navigate to the Settings menu use the DM32 Configurator software to re calibrate the touchscreen see the DM32 Configurator manual 4 11 Reset button If the touchscreen is frozen or your gauge is not functioning as normal you can reset your gauge 1 Use a paperclip to push the Reset button on the bottom of the gauge shown in Figure 3 2 The gauge screen will go blank while the gauge resets i...

Page 44: ...trotec s Manual Software Data Logger for details Virtual Gauge software mimics the screens of the gauge on the computer or device and can be used to control the gauge functions from the connected device in the same way that the gauge would be controlled by tapping on its screen Virtual Gauge thus offers users a way to remote control a gauge from a computer tablet or phone using the same interface ...

Page 45: ...ngs must be configured To connect directly to a computer use the following Network settings Status Wired Mode Static IP Address 169 254 1 1 or your computer specific loop back address Gateway 0 0 0 0 is actually ignored in this instance Subnet mask 255 255 0 0 so only the bottom two values of the IP Address are used If you have not changed the Network settings from the default values then the requ...

Page 46: ... a computer via Wired network When connecting multiple gauges to a computer the most reliable connection is the Wired Network Most computers only have a single Ethernet network connector so in order to connect multiple gauges a powered Ethernet switch or router must be used to group the gauges and feed a single Ethernet cable to the computer carrying information from all of the gauges as shown in ...

Page 47: ...e 57 and Figure 58 If more than one gauge is to be connected to a computer the customer must supply the switch router networking devices shown in the diagram The Router Creates a network The other devices then Join the network that has been created by the Router Figure 57 Multiple gauge connection and networking possibilities with the DM32 To connect the gauges to a computer via Wired network 1 Co...

Page 48: ...tap the Setttings Network Subnet mask key and use the numeric entry keypad to enter 255 255 0 0 Retrotec software FanTestic Virtual Gauge or Data Logger should be able to detect the gauges shortly after they are connected to the computer via Ethernet cable and the appropriate Network settings are chosen on the gauge If the white text on the Network key on the second Settings screen shows Not conne...

Page 49: ...ate 2 Tap the Setttings Network Mode key until you see DHCP 3 Go back to the Home screen and you should see the WiFi icon in the Top Bar Figure 59 Figure 59 Choosing WiFi Create or WiFi Join in Network Settings sets the Wireless icon in the Top Bar Figure 60 See the WiFi hotspot generated by the DM32 in the Wireless Network Connection panel on a PC To use the WiFi hotspot generated by the gauge ...

Page 50: ...he vicinity if they are plugged in to USB mains or PC power the WiFi will be working as they will automatically join the hotspot and could prevent another device from connecting 5 5 Make the DM32 join an existing WiFi network Another possibility for the operation of the WiFi is to have the DM32 connect to the same wireless network to which the computer is connected described here as WiFi Join This...

Page 51: ... Configurator software 4 The DM32 gauge serial number should show up on list automatically and you should highlight the gauge s you want to configure 5 Click the Network button one of the buttons along the bottom 6 Choose WiFi as the Network Status 7 Enter your WiFi router s Network Name SSID in the WiFi Settings section 8 If secure click on Secure Network and enter your WiFi router s Password 9 I...

Page 52: ...nfigurator showing up in Setttings Network Wireless settings If using Static IP addressing and you have entered the values directly using the IP address Subnet mask and Gateway keys or if you have entered them using the DM32 Configurator software you should see the values you entered displayed in Setttings Network ...

Page 53: ...nect the gauge to a computer via USB Using the USB connection to connect the gauge to a computer is necessary when updating the internal gauge software called firmware to get new features changing gauge settings for the Auto Zero interval re calibrating the touchscreen if the gauge touchscreen is inoperable Connect the gauge to a Windows based computer directly via USB cable between the USB port o...

Page 54: ...ny of the individual Retrotec software or a new version of FanTestic is installed To update the firmware version on the gauge it is mandatory to connect via USB and use the DM32 Configurator software i e updating firmware version on the gauge will not work if connected via an Ethernet Cable It is possible but not recommended to connect the gauge to a computer via USB and use FanTestic or the Virtu...

Page 55: ...d B If the pressure readings displayed on Channel A and Channel B match within 2 both that tube and the gauge ports used are OK To perform a tubing check 1 Display pressure for Channel B see section 3 3 9 2 Tap Settings Baseline Clear Baseline to remove any captured Baseline 3 Tap Settings Time Averaging and choose 5s 4 Connect a tube between Channel A and B on the gauge e g yellow and red pressur...

Page 56: ... in the label for Channel A Only if you see a huge problem should send your gauge back for factory calibration Pressure dropping to zero in 10 seconds indicates a leak somewhere try another tube and try the same tube on a different port to see which piece is faulty If the tube end is damaged slice 1 8 inch off the tube and try again To verify the gauge itself now that you know the tubes are in wor...

Page 57: ...The measured pressure on both channels should be within 2 of each other The same procedure can be followed to compare two gauges Connect the tube between corresponding ports on two gauges as shown in Figure 66 The reading on both gauges should be the same Figure 66 Gauge field check configuration Cross gauge check When performing a gauge calibration with two gauges if one gauge is known to be cali...

Page 58: ...10 If the gauge is fluctuating too much it will be difficult to read If the time averaging is too high the pressure may have changed but that change is not reflected in the reading Wind 25 10 These errors can be eliminated by long term averaging or by multiple pressure pickups Out of calibration 5 1 50 Gauges can go out of calibration in a week or may take 10 years It is impossible to tell unless ...

Page 59: ... will start and show the splash screen shortly 8 5 Pressing power button may not turn gauge On if battery is fully discharged When the gauge is fully discharged pressing the power button will not start the gauge It is necessary to plug the gauge in to mains power using the USB cable and AC power adapter When the gauge is being charged a red light on the front of the gauge bottom right corner will ...

Page 60: ...ngs If the measured values on Channel A or B are fluctuating back and forth in a way that doesn t correspond with any of the current testing conditions it s possible that the pressure tube is moving A moving tube can cause a significant error For instance a tube that is attached both to the gauge and to the fan but is in the path of the fan s air flow can swing back and forth This swinging motion ...

Page 61: ...re before calculating other results 8 11 Pressure can overshoot when using the Set Pressure key When Set Pressure is used to establish 60 Pa for example the fan can overshoot and reach up to 90 Pa for a few seconds before it settles back to the desired 60 Pa depending on the response time of the fan attached to the gauge If this is a concern start the fan on Set Speed or set to a lower pressure an...

Page 62: ...ge Read peak speed from gauge Read final speed from gauge Set the correct Device on your gauge because it will calculate different results depending on which Device is selected 8 12 Check if large fixed errors are caused by pinched tubes A pinched pressure tube can create a very high reading on the gauge which is erroneous In other cases a pinched tube will prevent the pressure measurement from re...

Page 63: ...d of the tube Water can cause either a positive or a negative pressure based on which way the drop of water is pulling If a drop of water is facing downward it pulls out of the tube creating a negative pressure as displayed in Figure 69 Point the tube upward and the water drop falls back into the tube creating a positive pressure Figure 69 Water in the reference tube left high fixed pressure due t...

Page 64: ...he rule of thumb here is to wait for at least double the time average period before a reading is taken Time Avg exercise to practice reducing the effects of wind 1 Use a fan to create an air stream 2 Set Time Averaging to 1 s 3 Place a tube connected to the positive port in the path of the air stream 4 The gauge will display a pressure that fluctuates Adjust the wind speed until the gauge is readi...

Page 65: ...he main pressure pickup point into either two or four directions which will average the fluctuation across the building Recent experience has shown that longer time averaging on a digital gauge is almost as effective as the four tube wind damping kit When the time taken to set up the kit is taken into account increasing the time averaging will actually save time A wind damping system averages out ...

Page 66: ...eveloped when the wind hits the wall If pressure is still too high place a T on the end of the tube and tape it to the middle of a plastic dinner plate or smaller plate Tape the T to the concave surface of the plate which is the one that would normally be facing up Invert the plate on the ground so the plate covers the tube This will prevent the velocity from impinging on the end of the tube If fu...

Page 67: ...urrent draw WiFi ENABLED 430 mA and will last approx 9 hours on a single charge Display Size Type 3 2 inch 8 2 cm QVGA touch screen display with backlight Microcontroller 32 bit Channels 2 Sensor Type Digital Pressure Range 5 in WC 1244 Pa Pressure Resolution 0 1 Pa 0 0004 in WC 0 002 psf Temperature compensated 0 C to 50 C operating 40 C to 85C storage 40 C to 85C humidity 0 to 95 RH Overpressure...

Page 68: ...column 1 in WC is the amount of pressure required to suck water up a straw to a height of one inch One inch of water column in WC 249 Pa 5 2 psf To measure a pressure 1 Connect a pressure tube to the blue port of the gauge 2 Press On 3 Place the end of the tube into a glass of water slightly more than 1 inch below the surface 4 The gauge will display around 1 00 in WC or 249 Pa or 5 2 psf dependin...

Page 69: ...d will cause that pressure to go up to 55 Pa and down to 45 Pa making it very difficult to take a reading There are other reasons a large Bias or Baseline pressure can appear on the gauge and these should be eliminated first before assuming wind is causing the problem If the tube is being moved by the wind a large rapidly fluctuating pressure will appear but can easily be eliminated by taping or t...

Page 70: ... these methods gives a list you can go by if Baseline pressures are above 2 Pa or you simply want to increase repeatability Your outdoor pressure pickup tube should 1 Be 15 feet from the building 2 Terminate in a T 3 Have 2 pickup points at least 20 feet apart attached to either side of the T 4 Each point should be covered with a flat plate or box These steps will reduce the magnitude and variatio...

Page 71: ... connect the gauge to a Retrotec fan or variable speed fan drive 1 Locate the end of the Umbilical cable this is the bundle of pressure tubing and Control Cable with the shortest length of exposed pressure tubes and Control Cable Plug the yellow Control Cable into the Fan Speed Control port on the gauge 2 Plug colored tubes into the matching color coded pressure ports on the top side of the gauge ...

Page 72: ...ilding pressure 9 To view estimated flow at the exact target pressure use the Pressure function 10 Tap Channel A to Hold the results on the display to make them easier to copy down The gauge calculates Flow based on Pressure readings from the fan The air flow being produced by the calibrated fan is a value that can be calculated based on the pressure developed by the air moving across the inlet si...

Page 73: ...al Fan Pressure across the inlet Channel B will thus show a pressure difference that is larger than the actual fan pressure larger by an amount equal to the induced room pressure being measured on Channel A Any time the gauge sees a positive pressure on Channel A it automatically subtracts the value on Channel A from the value on Channel B before calculating flow and other results The value displa...

Page 74: ...8 0 1150 1 0 8 6 A 0 5030 264 9959 0 075 1 0 0 0 1 0 12 B 0 5000 174 8824 0 000 0 3 0 0 1 0 10 C8 0 5000 78 5000 0 020 0 5 0 0160 1 0 10 C6 0 5050 61 3000 0 054 0 5 0 0040 1 0 10 C4 0 5077 42 0000 0 009 0 5 0 0009 1 0 10 C2 0 5200 22 0000 0 11 0 5 0 0010 1 0 10 C1 0 5410 11 9239 0 13 0 4 0 0014 1 0 10 L4 0 4800 4 0995 0 003 1 0 0 0004 1 0 10 L2 0 5020 2 0678 0 000 0 5 0 0001 1 0 10 L1 0 4925 1 161...

Page 75: ...F DU100 Open 0 4910 39 4840 0 000 1 0 0 0000 1 0 10 2 75 0 5110 3 0110 0 000 1 0 0 0000 1 0 10 1 23 0 5110 1 1290 0 000 1 0 0 0000 1 0 10 Retrotec 600 700 Open 0 5280 372 5200 0 000 1 0 0 0000 1 0 10 12 0 5000 104 6800 0 000 1 0 0 0000 1 0 10 8 0 5000 54 0300 0 000 1 0 0 0000 1 0 10 6 0 5000 24 1250 0 000 1 0 0 0000 1 0 10 2 0 5000 8 2400 0 000 1 0 0 0000 1 0 10 1 0 5000 4 0700 0 000 1 0 0 0000 1 ...

Page 76: ...he above equation substitute 50 for 25 if 50 Pa is the required test pressure The actual flow exponent n for an enclosure can be calculated by measuring building leakage at multiple pressure differences from 10 to 50 Pa and determining the slope of the line Flow K 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒𝑛 The graph of pressure versus flow will be linear if graphed on a log log scale and the slope will be n The Flow equation is u...

Page 77: ...lation 1000 𝐶𝐹𝑀 1 39 1390 𝐶𝐹𝑀 Thus the estimated result for CFM at 50 Pa will be 1390 CFM The factors depend on the n value chosen and Table 10 is for n of 0 65 which is typical for houses Table 10 Factors for when a building pressure of 50 Pa cannot be reached n value of 0 65 Pressure achieved Cannot reach 50 factor Pressure achieved Cannot reach 50 factor 50 1 00 25 1 57 49 1 01 24 1 61 48 1 03 ...

Page 78: ...e if you read 600 CFM at a building pressure of 19 Pa the Cannot reach 25 Pa factor from the table is 1 18 Make the following calculation 600 𝐶𝐹𝑀 1 18 708 𝐶𝐹𝑀 Thus the estimated result for CFM at 25 Pa will be 708 CFM The factors depend on the n value chosen and Table 13 is for n of 0 6 which is typical for duct systems Table 11 Factors for when a building pressure of 25 Pa cannot be reached n val...

Page 79: ...he flow doubles That is due to completely turbulent flow going through that hole flow square root of pressure a constant for that particular hole 𝑓𝑙𝑜𝑤 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒0 5 An n value of 1 0 represents tiny little holes so small that the air would not be turbulent but rather would go through the holes as laminar flow This means that when pressure is quadrupled the flow will also be quadrupled 𝑓𝑙𝑜𝑤 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒1...

Page 80: ... for Pressure extrapolation The n value is a number set between 0 5 and 1 0 that is used to extrapolate Channel B results to a pressure that is not the pressure read on Channel A It can be changed by tapping Settings Ducts 0 6 House 0 65 Set it to 0 65 for houses and 0 60 for ductwork Set to 0 5 for tests using the Retrotec House or duct simulator air handler flow and any large hole that is not co...

Page 81: ... 0 7 but this is unknown Instead 0 6 will be used The gauge would calculate 𝐹𝑙𝑜𝑤 25 𝑃𝑎 25𝑛 𝐶𝐹𝑀 20𝑛 𝐹𝑙𝑜𝑤 25 𝑃𝑎 250 6 100 200 6 𝐹𝑙𝑜𝑤 25 𝑃𝑎 114 𝐶𝐹𝑀 However if it was known that n was 0 7 the flow at 25 should have been 𝐹𝑙𝑜𝑤 25 𝑃𝑎 250 7 100 200 7 𝐹𝑙𝑜𝑤 25 𝑃𝑎 117 𝐶𝐹𝑀 This value is less than 3 off from what it should be If the test pressure was within 1 or 2 Pa of the reference pressure of 25 Pa the Pres...

Page 82: ... of Enclosure 0 50 0 55 0 60 0 65 0 70 0 75 Achieved Pressure Pa 10 14 9 7 7 0 0 8 4 17 5 27 3 15 11 3 5 8 0 0 6 2 12 8 19 8 20 8 8 4 5 0 0 4 7 9 6 14 7 25 6 7 3 4 0 0 3 5 7 2 11 0 30 5 0 2 5 0 0 2 6 5 2 8 0 35 3 5 1 8 0 0 1 8 3 6 5 5 40 2 2 1 1 0 0 1 1 2 3 3 4 45 1 0 0 5 0 0 0 5 1 1 1 6 50 0 0 0 0 0 0 0 0 0 0 0 0 55 1 0 0 5 0 0 0 5 0 9 1 4 60 1 8 0 9 0 0 0 9 1 8 2 7 65 2 7 1 3 0 0 1 3 2 6 3 9 70 ...

Page 83: ...Page 83 of 91 Retrotec 2017 Flow C 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒𝑛 The graph of pressure versus flow will be linear if graphed on a log log scale and the slope will be n ...

Page 84: ...860 0 856 0 852 0 848 0 844 0 0 886 0 882 0 878 0 874 0 869 0 865 0 861 0 857 0 854 5 0 896 0 892 0 887 0 883 0 879 0 875 0 871 0 867 0 863 10 0 906 0 901 0 897 0 893 0 888 0 884 0 880 0 876 0 872 15 0 915 0 911 0 906 0 902 0 898 0 894 0 890 0 885 0 881 20 0 925 0 920 0 916 0 912 0 907 0 903 0 899 0 895 0 891 25 0 935 0 930 0 926 0 921 0 917 0 912 0 908 0 904 0 900 30 0 944 0 940 0 935 0 931 0 926...

Page 85: ... 998 1 007 1 017 1 027 1 037 1 047 1 056 1 066 1 076 40 0 993 1 002 1 012 1 022 1 032 1 041 1 051 1 061 1 070 45 0 988 0 997 1 007 1 017 1 026 1 036 1 046 1 055 1 065 50 0 983 0 992 1 002 1 012 1 021 1 031 1 041 1 050 1 060 55 0 978 0 988 0 997 1 007 1 016 1 026 1 036 1 045 1 055 60 0 973 0 983 0 992 1 002 1 011 1 021 1 031 1 040 1 050 65 0 969 0 978 0 988 0 997 1 007 1 016 1 026 1 035 1 045 70 0 ...

Page 86: ...auge on the correct Range Use the Flow Conversion Chart for your fan to locate the correct results as follows In this example you were testing with a DU200 DucTester with Range Device on the gauge set to Mid Later you remembered your DucTester actually had the Low Range Ring attached You recorded 33 CFM Find the 33 CFM you recorded under the Mid column for Range on the Flow Conversion Table Then j...

Page 87: ... only one layer thick This is the flow measuring hole For accuracy the small hole should be at least 1 5 inches from the edge of the box and its area should be less than half the area of the end of the box 3 Tape any cracks in the other sides of the box to prevent air from leaking 4 Punch a 0 25 inch diameter hole near a corner of the open end of the box for the pressure tube Insert a tube in the ...

Page 88: ...s will decrease the exhaust fan flow rate Box pressures below 3 Pa are less accurate because small fluctuations in pressure will affect the flow a lot One Pa is a practical limit for measuring flow below which readings cannot be taken Try the same fan with different holes to see the different results ...

Page 89: ...ressure in the enclosure by blowing air out of it Air is drawn in from outside to replace it showing up as geysers when checked with an air current tester digital gauge A gauge with an electronic pressure sensor and digital display that is capable of reading in tenths of a Pascal Door Fan A test instrument that fits into an open doorway in order to pressurize or depressurize an enclosure It is a c...

Page 90: ...rate See ASTM E779 10 eq 5 Fan Pressure The pressure difference between inside the door fan and the surrounding air This pressure can be read as PrB from Channel B on the gauge It is used by the computer to calculate the air flow rate through the Door Fan Fan Top Part on the fan where the fan s tubing Control Cable and power connections are HVAC Heating Ventilating and Air conditioning system Leak...

Page 91: ...put Control port on the gauge to control fan speed labeled Speed Control time averaging Refers to the digital gauge display that must have an adjustable averaging from 1 second to 1 minute for the purpose of averaging fluctuating pressure signals Averaging can be block averages that will update for the length of the average or rolling moving averages that will update continuously by displaying the...

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