Operating Instructions for Models Cobra and Lynx Air and Duct Leakage Testers: (Inlet Damper and Digital Gauges)

Transcription

1 Operating Instructions for Models Cobra and Lynx Air and Duct Leakage Testers: (Inlet Damper and Digital Gauges)

2 Table of Contents Introduction Introduction.. 2 Safety Precautions Safety Precautions. 2 Assembly Assembly - Included parts 3 Assembly - Installing orifice plate. 3 Assembly - Joining orifice tube sections.. 4 Assembly - Connecting pressure tubing.. 5 Assembly - Calibration certificate. 5 Duct Leakage Testing Operating the Equipment Pre-test Checklist. 6 Extension Cord Requirements... 6 Orifice Plate Flow Ranges.. 7 Preparing Duct System for Testing 8 Connect Flexible Duct to Orifice Tube.. 8 Connect Flexible Duct to Duct System. 8 System Test Pressure Connection. 8 Duct Leakage Test Setup (SUPPLY). 9 Duct Leakage Test Setup (RETURN/EXHAUST)... 9 Zero the Pressure Gauges.. 10 Starting the Blower 10 Obtaining System Test Pressure. 11 Determining Leakage Rate Troubleshooting Zero reading on DUCT SYSTEM gauge Zero reading on ORIFICE TUBE gauge.. 15 Can t obtain system test pressure ORIFICE TUBE gauge reading maxed out

3 Introduction These operating instructions are for ORIFLOW models Cobra and Lynx duct leakage testers outfitted with the optional digital gauges. Both models are exactly the same as the standard Cobra and Lynx testers with the exception that both are outfitted with digital pressure gauges instead of Magnehelic gauges. Your duct leakage tester requires minimal assembly which is described in the next section. Safety Precautions Before operating the tester, read the following safety precautions: DO NOT operate the tester in the rain, DO NOT operate the tester while it is near or in water, DO NOT operate the tester with a damaged electrical cord or plug, DO NOT remove the inlet safety screen, DO NOT touch the blower wheel when the unit is plugged in, DO NOT look into the discharge end of the tester when the unit is plugged in, DO NOT use the tester as a ladder or step stool, DO NOT allow children near the tester, DO use an extension cord of the proper gauge (see Table 2), DO use the proper voltage and line frequency listed on the motor nameplate, DO lock the caster when the tester is positioned horizontally, DO use the tester on level ground, DO secure the tester when transporting it, DO wear proper hearing protection, safety glasses and work gloves, DO seek assistance when lifting the tester (e.g., loading onto truck, going up or down stairs). 2

4 Assembly Included Parts Upon arrival, your Cobra or Lynx leak tester will come preassembled except for the top half of the orifice tube. See Table 1 for the individual items that are included with your tester. Table 1 List of Loose Parts Item Quantity Comment Leak tester 1 Orifice tube section 1 Hardware wing nuts 6 Hardware - bolts 6 Fully assembled except for orifice and orifice tube section. Section will be loose and wrapped to protect during shipment. Must attach to bottom half of orifice tube using included wing nuts and bolts. See instructions in steps below. Use with included bolts to join the two sections of orifice tube together. Use with included wing nuts to join the two sections of orifice tube together. Calibration certificate 1* This should be already mounted to the front of your testers. Flex-duct 12.5 ft This will be coiled around the rear of the tester. Worm gear clamp 1 Use this to connect flex-duct to orifice tube end. * you will receive as many calibration certificates as the number of orifice plates ordered; one certificate goes with each orifice plate (testers come with choice of one orifice plate; other plates may be purchased separately). Assembly - Place orifice plate between tube sections as shown in Figure 1 and Figure 2. Figure 1 Placing Orifice Plate 3

5 Figure 2 Install tube section Using the included wing nuts and bolts, join the two orifice tube halves together. Figure 3 Joining Orifice Tube Sections together Connect the pressure tubing from the pressure gage marked ORIFICE TUBE to the pressure tap marked P2 located on the top half of the orifice tube (see Figure 4). Notice that the other pressure tubing from this gauge will already be connected to the bottom half of the orifice tube on the pressure port marked P1. 4

6 P2 Figure 4 Connecting Loose Tubing to Pressure Tap Finally, refer to the correct calibration certificate that matches the orifice plate that was installed. Each plate has an engraved serial number that matches the serial number listed on the corresponding calibration certificate. You are now ready to perform a duct leakage test. See the next section for the proper steps to perform duct leakage testing. 5

7 Duct Leakage Testing Operating the Equipment Pretest Checklist Go through the following list BEFORE transporting equipment to the jobsite: 1. Do you have adequate voltage and amperage for your tester? 110V/20A is preferred but 110V/15A is adequate (see Starting the Blower section). 2. If you need an extension cord, is it the proper gauge? See Table 2 below for typical requirements for a blower requiring 15 amps of current at 110 volts. Table 2 Recommended Extension Cord Gauge Extension Cord Required Gauge Length (feet) Make sure you have enough flexible-duct with your tester for the job. Each tester includes 12.5 feet, which is enough for most applications. Extra lengths of flexible-duct are available at 4. Determine the allowable leakage for the project using data given. To help with your calculations, use ORIFLOW s free online programs to make these calculations ( Calculations are done for either of the two typical specifications: percentage of system flow, or leakage class. 5. After determining the allowable leakage, make sure that value is located on your included calibration certificate. If not, you probably will need a different orifice plate. See the following tables to see the capacities of each orifice plate with both leak testers (Cobra and Lynx). 6

8 Table 3 Tester Capacities using the 1-inch Orifice Plate COBRA System Static Minimum LYNX Tester Tester Pressure Flow Rate* Maximum Maximum (in.wg.) (cfm) Flow Rate Flow Rate (cfm) (cfm) Table 4 Tester Capacities using the 2-inch Orifice Plate COBRA System Static Minimum LYNX Tester Tester Pressure Flow Rate* Maximum Maximum (in.wg.) (cfm) Flow Rate Flow Rate (cfm) (cfm) Table 5 Tester Capacities using the 3-inch Orifice Plate COBRA System Static LYNX Tester Minimum Tester Pressure Maximum Flow Rate* Maximum (in.wg.) Flow Rate (cfm) Flow Rate (cfm) (cfm) Table 6 Tester Capacities using the 4-inch Orifice Plate COBRA LYNX Tester System Static Minimum Tester Maximum Pressure Flow Rate* Maximum Flow Rate (in.wg.) (cfm) Flow Rate (cfm)

9 Preparing Duct System for Testing Cap off all ends of system using clear plastic and duct tape or duct end caps. Make sure you test the part of the duct system that leakage testing is required. Usually, this is from the system fan up to, but not including, the VAV boxes (terminal units). Connect Flexible Duct to Orifice Tube See the figures below for securing one end of the flexible duct to the orifice tube. Note that the worm-gear clamp should be slid over the duct before connecting it to the orifice tube. Slide the flexible duct so that it overlaps the orifice tube1 to 2 inches, and tighten clamp using a 5/16-inch nut driver. Figure 5 Installing Flex-Duct on Tube Figure 6 Tightening Clamp Connect Flexible Duct to Duct System Find a convenient location in the duct system where the flexible duct from the leakage tester will connect to. Make sure that the connection where you connect the flexible duct is a sturdy, sealed tight connection. You don t want to create a leaky connection right where the tester is supplying air into the system. System Test Pressure Connection So that you know what static pressure the system is being tested at, you need to drill a hole at least 3 feet away from the flex-duct connection. Drill a 3/8-inch diameter hole and insert the pressure tubing from the gauge marked Duct System. Note both testers come with at least 20 feet of pressure tubing. Insert the pressure tubing from the DUCT SYSTEM gauge so that 6 to 12 inches of tubing is inside the duct system. Using putty or duct tape, seal the connection. See Figure 7 showing a duct leakage test setup for SUPPLY systems. Refer to Figure 8 for the test setup required to measure air leakage of a RETURN/EXHAUST system. 8

10 Figure 7 Duct Leakage Test for a SUPPLY System Figure 8 Duct Leakage Test for a RETURN/EXHAUST System 9

11 Zero the Pressure Gauges Before you run the tester, make sure both gauges read zero pressure when the unit is off and there is no pressure being applied to the digital gauges. If either gauge requires zeroing, follow these steps: With the gauge reading pressure (home position), press and hold the MENU button, Press the button until the display shows the AdU MENU, Press the E button to show the submenu, Auto ZERO, For accurate zeroing of the gauge, do not apply any pressure, With the display reading Auto ZERO, press the E button, the display will blink, Press the E key again to complete the auto-zero function. Starting the Blower Before operating your duct leakage tester, make sure you have access to 110V, 15A power. Doing this before starting the blower will insure that the blower sees the least amount of load upon startup. Note that you may trip the circuit breaker the time you turn the blower on. A simple way around this is to spin the impeller of the fan before turning the blower on. DO NOT use fingers or hand. Before switching the blower on, make sure the inlet damper is fully closed. Figure 9 Shut damper closed before starting blower (Cobra shown). 10

12 Obtaining System Test Pressure Adjust fan Inlet slowly to obtain system test pressure. Keep your eye on the DUCT SYSTEM gauge while opening the fan inlet. When you have reached the required system static pressure, lock or set the inlet damper. See Figures 10 through 12. Figure 10 adjust inlet damper until test pressure is reached (Cobra shown) Figure 11 pay attention to DUCT SYSTEM gauge reading while adjusting inlet damper 11

13 Determining the Leakage Rate Now that you have obtained the system test pressure and have the inlet damper locked in position (Figure 12), note the pressure reading of the ORIFICE TUBE gauge (Figure 13). Refer to your calibration certificate to determine the leakage rate that corresponds to the gauge reading. An example of a calibration certificate is shown in Figure 14; it is for informational purposes only and used in the example shown on the next page. Always refer to the calibration certificate that came with your calibrated orifice plate. Figure 12 set and lock the position of the inlet damper when you reach test pressure (Cobra shown) Figure 13 ORIFICE TUBE gauge reading 12

14 SAMPLE CALIBRATION CHART TABE BELOW FOR EXAMPLE ONLY USE YOUR CHART Figure 14 Use calibration certificate table to convert gauge reading to leakage Note there every calibration chart always has an equation you can use that is given below the table Example For an ORIFICE TUBE gauge reading of 1.1 in.wg., the leakage rate is cfm. For an exact value, use the equation that comes with every calibration certificate. It will look like this: Leakage = x, where the value of is a constant and will be specific to the orifice plate used (every plate has its own value; yours will be different). Using a calculator or spreadsheet, take the square root of the gauge reading first, and then multiply by the constant for your orifice plate. 13

15 Troubleshooting Zero reading on DUCT SYSTEM gauge If the gauge reading is zero, refer to the table below to fix this problem. Perform troubleshooting steps in the order shown in the Table 7 below. Table 7 Troubleshooting steps when DUCT SYSTEM gauge is zero Step Scenario What to do Inlet damper was left shut, cutting off air to the system. Pressure tubing connected to gauge incorrectly Plugged fitting or malfunctioning gauge. Open inlet damper slowly. Look at the P1 and P2 stickers that are located on the orifice tube and gauges. Make sure tubing from P1 tap matches the P1 tap on the ORIFICE TUBE gauge. Gently blow through other end of pressure tubing from DUCT SYSTEM gauge, and watch needle increase pressure reading. Check for these other sources of leakage: 4 System is leaking too much air. Rectangular duct joints (check and seal corners), Fire or smoke dampers, Duct joints (pay particular attention to flex-duct joints if they are part of the leak test), VAV boxes (pay particular attention to parallel box back draft dampers), Built-up air handlers, Plenums, Uncured duct sealant blow-thru (follow manufacturer instructions for cure time), Improperly sealed or un-sealed joints, Hot water coils and electric heaters, Open duct end that was supposed to be sealed/capped-off for the leak test. 14

16 Zero reading on ORIFICE TUBE gauge If the gauge reading is zero, refer to the table below to fix this problem. Perform troubleshooting steps in the order shown in Table 8 below. Table 8 Troubleshooting steps when ORIFICE TUBE gauge is zero Step Scenario What to do 1 Inlet damper was left shut, cutting off air to the system. 2 Plugged pressure taps. 3 Orifice plate too large for application. Open inlet damper slowly. Remove pressure tubing from ORIFICE TUBE gauge, and blow through each end to make sure the pressure taps on the orifice tube are clear. If you are using a 4-inch ID orifice plate, and the system is leaking 40 cfm, you probably won t even notice the gauge needle moving. This can happen to other orifice plates too. You need to purchase an orifice plate with a smaller bore diameter so that a small amount of airflow/leakage will result in a bigger pressure drop. 4 4 System is leaking very little air. Pressure tubing connected incorrectly. You ll know if this is true if the fan inlet is almost shut. Not likely unless system is small. Fix is to use plate with smaller bore. Look at the P1 and P2 stickers that are located on the orifice tube and gauges. Make sure they match. 5 Malfunctioning gauge. 6 Not sure Remove the clear pressure tubing from the lower pressure tap on the orifice tube and blow through the end of the tubing. The needle should move in response. If not, the gauge is faulty. The best way to make sure that your tester is working properly is to disconnect the flex duct from the system and turn the blower on, and slowly open the inlet damper. If you feel a lot of air coming out of the tube end, you should see a pressure reading on the gauge ORIFICE TUBE. Can t obtain system test pressure This happens when the system is leaking too much air. Make sure all outlets are sealed. Check corners of rectangular duct for excessive leakage. Inspect all duct and fitting joints for leakage. Make sure you seal all suspect joints and allow to cure 24 to 48 hours. Always refer to duct sealant manufacturer s instructions. Check for these other sources of leakage: Rectangular duct joints (check and seal corners), Fire or smoke dampers, Duct joints (pay particular attention to flex-duct joints if they are part of the leak test), VAV boxes (pay particular attention to parallel box back draft dampers), Built-up air handlers, Plenums, 15

17 Uncured duct sealant blow-thru (follow manufacturer instructions for cure time), Improperly sealed or un-sealed joints, Hot water coils and electric heaters, Open duct end that was supposed to be sealed/capped-off for the leak test. A non-toxic smoke machine is an excellent tool for locating significant sources of leakage. Call ORIFLOW at or online at for more information. ORIFICE TUBE gauge reading maxed out Scenario 1: The system is leaking too much air. Make sure all outlets are sealed. Check corners of rectangular duct for excessive leakage. Inspect all duct and fitting joints for leakage. Make sure you seal all suspect joints and allow curing time of 24 to 48 hours. Always refer to duct sealant manufacturer s instructions. Scenario 2: orifice plate bore could be too small, causing a high pressure drop at low to moderate flows. You need an orifice plate with a larger bore. ORIFLOW LLC Clearwater, Florida (phone) 8am to 5pm PST (fax) sales@oriflow.com engineering@oriflow.com 16