LNG Regulator Test Kit

Transcription

1 OVERVIEW Chart provides a LNG Economizer/Regulator Test Kit to help save money and time by allowing a technician to more accurately and easily diagnose the operability of the pressure control regulator/economizer (referred to from here on as the economizer), and the 2 PSI check valve if a low tank pressure condition is exhibited. The economizer is used to re-refrigerate the tanks, and the 2 psi check valve in the tank knuckle aids the economizer in its function. PARTS The LNG Economizer/Regulator Test Kit. PN: is available through LNG Regulator Test Kit LNG Economizer/Regulator Test Kit can be used with a high pressure or low pressure nitrogen gas supply. Minimum supply pressure should be 25 psi (1.7 bar) above desired economizer setting. Note: It is recommended but not imperative, to empty the LNG from the tank for this test. Page 1 of 8

2 Two Types of Economizers There are two types of economizers, adjustable & non adjustable: Adjustable economizers will have an adjustment screw and locking nut. The non-adjustable will be preset to a fixed pressure and the adjustment screw will be locked in position and cutoff. If a non-adjustable economizer is found to be out of specifications it will need to be replaced. Contact Chart LNG Technical Service with the LNG tank serial number for an economizer replacement part number. Safety DO NOT use shop air to operate the LNG Economizer/Regulator Test Kit as this could create a flammable mixture inside the tank. Use nitrogen only Testing should be performed in well ventilated areas. Over Pressure Relief Valve Cap MUST be in place on the pressure relief valve. Re-install or replace if missing or damaged PN: Appropriate personal protection should be worn. Safety glasses, gloves, ear plugs, etc... Become familiar with the tank components that will be used. Page 2 of 8

3 Determining Set-Point & Adjusting the Economizer on Single Standard, Single Integrated, & Dual Integrated Tanks Step 1: Vent the tank pressure to 20 psig (1.4bar) below the indicated pressure setting of the economizer, or 90psi/6.2bar, whichever is the highest pressure. Venting below 90psi/6.2bar can de-saturate the fuel and cause low pressure/poor engine performance issues. The indicated pressure can be found etched onto the economizer above the side port. Step 2: Connect the LNG Economizer/Regulator Test Kit to the acceptable source of nitrogen gas. Step 3: Close the Liquid shutoff valve (red handle) on the LNG tank then operate the truck engine to consume remaining fuel in the lines from the tank to the engine prior to performing next step. This will release most of the pressure from the lines and components in the system. NOTE: There will be residual pressure in the fuel line that will need to be released Page 3 of 8

4 Step 4: Identify the Tank Type & Locate Connection point Page 4 of 8

5 Step 5: Connect the LNG Economizer/Regulator Test Kit tubing to the FUEL bulkhead fitting on the top of the LNG tank: There will be residual pressure in the fuel line that will need to be released before removing tubing. a) Standard Single tanks, disconnect the fuel line and remove elbow at the fitting labeled FUEL or LIQUID on the top of the LNG tank shroud (12 o clock position). b) Standard Dual tanks, tanks, disconnect the fuel line and remove elbow at the fitting labeled FUEL or LIQUID on the top of the LNG tank shroud (12 o clock position). c) Integrated Single tanks, disconnect the fuel line and remove elbow at the fitting labeled FUEL or LIQUID on the shroud of the LNG tank shroud (2 o clock for left tanks & 10 o clock position for right tanks). d) Integrated Dual tanks, disconnect the fuel line and remove elbow at the fitting labeled AUX LIQUID IN or FUEL on the shroud of the LNG tank shroud (2 o clock for left tanks & 10 o clock position for right tanks). Note: When performing this test on a dual tank system, you must connect to & test each tank individually. Step 6: Open the Liquid Shutoff Valve (red handle) on the LNG tank. On the test kit, close the Pressure Release Valve and adjust the nitrogen Pressure Regulator Valve until outlet pressure is slightly (~5 psig 0.34 bar) above the pressure indicated on the LNG tank pressure gauge and nitrogen gas begins to flow into the LNG tank. The flow should be in the 5-20 scfh range. This flow is going through the internal 2 psi check valve weep hole, not through the economizer. The economizer should be closed at this point. Page 5 of 8

6 Note: When test kit regulator outlet pressure is increased to approximately 5psi/0.3bar above LNG tank pressure (tank pressure should be 20psi/1.4bar below indicated economizer setting, but not below 90psi/6.2bar), a flow of 5-20 scfh is expected and normal. If the flow meter exceeds 20scfh at these pressure settings either the economizer or the internal 2 psi check valve and/or the economizer is stuck open. If this happens, proceed to Step 20. Caution: Never exceed 150 psig (10.34bar) during this test as damage to the flowmeter could occur. Re-install or replace Over Pressure Relief Valve Cap if missing or damaged. PN: Step 7: While observing the flow meter, slowly increase the nitrogen gas pressure by adjusting the regulator pressure valve until the flow rapidly increases to the scfh range to open the economizer. Step 8: While observing the flow meter, slowly decrease the pressure by adjusting the regulator pressure valve. Stop at the point at which the flow stops rapidly falling and stabilizes. Note flow reading. Slowly increase the pressure until flow increases 10 scfh above previous reading (the economizer is considered open at 10 scfh of flow). Read the regulator outlet pressure gauge. This reading is the economizer s pressure set point. Example: Initial flow stabilizes at 15 scfh, adjust pressure up until flow is 25 scfh. The indicated pressure on the outlet gauge is the economizer s set point. Note: Economizer set point reading must be within +/- 5psi (0.34 bar) from the desired set point. Step 9: If adjustment is needed go to Step 14. Otherwise, close the Liquid Shutoff Valve, gas supply, and slowly open pressure release valve before removing the test equipment. Page 6 of 8

7 Step 14: Determine if the Economizer is adjustable. Adjusting an Adjustable Economizer Set Point Step 15: Adjust the nitrogen gas pressure to 5psi/0.3bar above the desired set pressure by adjusting the regulator pressure valve. Step 16: If there is no flow through regulator, loosen the lock nut (counter-clockwise) on the economizer, and then loosen the adjustment screw (counter-clockwise) until flow increases to the scfh range. Step 17: If the flow through the regulator is at least 60 scfh (if flow is not at least 60 scfh, loosen lock nut & loosen adjustment screw (counter-clockwise) until at least 60 scfh is reached): A With locknut loosened, slowly tighten the economizer s adjustment screw (clockwise), until the flow meter ball stops dropping (Flow will stabilize in the 5-20 scfh range). Record the flow reading from the flow meter. Example: 12 scfh B Take the flow reading from Step 17 (A) and add 10 scfh (the economizer is considered open at 10 scfh of flow), this will be the desired setting. Example: 12 scfh + 10 scfh = 22 scfh C - Loosen the economizer s adjusting screw (counter clockwise) until the flow is scfh higher than desired setting or at maximum regulator flow. Example: 22scfh desired setting + 30 scfh = 52 scfh (If flow is not adjusted scfh higher than desired setting, adjustment will fail to reach desired setting.) D - Tighten adjustment screw (clockwise) until flow is returned to the desired setting. Example 22 scfh (Note: Do Not Overtighten. If adjustment screw is tightened to the point where flow falls below the desired level, you must return to step C above as adjustment will fail to reach desired setting.) Step 18: Tighten locking nut (clockwise) while using a second wrench to secure adjustment screw from turning. Step 19: Check to ensure desired psi set point by repeating Steps 6-8. Repeat adjustment procedure if adjustment is needed. If set to desired set point, close the Liquid Shutoff Valve (red handled valve), close gas supply, and slowly open pressure release valve before removing the test equipment. NOTE: If at any point during testing defective parts are found, replace as needed. Page 7 of 8

8 Troubleshooting the Economizer After economizer settings have been determined the economizers can be tested for functionality. Step 20: Defrost tank plumbing by spraying with a water hose, heating with a heat gun, or allowing it to defrost naturally. Step 21: Close liquid shut-off (red handled valve) on one LNG tank, and leave the liquid shut-off (red handled valve) valve on the other tank open. This will enable testing of one economizer at a time. Step 22: Start truck and allow to run. Observe economizer and J-tube of tank with the open liquid shut-off/red handled valve. If LNG tank pressure is below economizer setting pressure of that tank, the economizer should be closed and there should be no fuel moving through the economizer, and therefore no frost should be on economizer and J-tube. If frost starts to form at the stainless pipes leading into the economizer or the economizer outlet elbow, and the tank pressure is below economizer setting pressure, the economizer is not closing properly. If frost forms only on the upper right side of the copper tube, or only at the tank knuckle, the economizer is closed and is functioning properly at that time. Note: If you see the tube frost at the right side extending down toward the lower most portion (bottom of the U) but not on the left side of the copper tube, and none of the components the economizer are frosted (no frost on the left side of tube and back through economizer) the economizer is functioning properly. This would indicate that some liquid has entered the knuckle cavity and possibly spilled into the tube from the right side through the knuckle check valve. For dual tank systems repeat Steps for the other LNG tank. Page 8 of 8