10 psig
While leak testing a low-pressure chiller with nitrogen, the maximum pressure should not exceed 10 psig. If it exceeds 10 psig, the rupture disc will burst open.
What is the lowest access point on a low-pressure centrifugal air-conditioning appliance?
The evaporator charging valve is the lowest access point on all centrifugal chillers and air-conditioning appliances.
Where is the rupture disc located on a centrifugal chiller?
25 Cards in this Set
| Where is the rupture disc located on a centrifugal chiller? | Evaporator |
| A hydrostatic tube test kit will; | Determine if a tube leaks. |
How do low-pressure chillers operate?
A chiller works on the principle of vapor compression or vapor absorption. As the heat-transfer takes place, the refrigerant evaporates, changing from a low-pressure liquid into vapor, while the temperature of the process coolant reduces. The refrigerant then flows to a compressor, which performs multiple functions.
When adding nitrogen to a system for leak detection What is the maximum pressure that should be applied to the system?
2. Pressure-dependent leaks:Pressure-dependent leaks are leaks that can only be detected as the system pressure increases. Nitrogen is used to pressurize the low sides of systems to around 150 psig, and high sides to 450 psig. Never use air or pure oxygen.
What is the maximum pressure that should be used for leak testing a refrigeration system with a hermetic compressor?
The low side should not be pressurized above 150 psig and the high side above 450 psig. In the field, the entire system should be limited to 150 psig while looking for leaks.
Which of the following safety precautions should be adhered to for low-pressure systems?
Which of the following safety precautions should be adhered to for low pressure systems? -Do not syphon refrigerant by mouth. -Avoid spilling refrigerant on the skin. -Use gloves and safety goggles when working with liquid refrigerant.
What is the most efficient method for leak checking a charged low-pressure refrigeration unit?
The most efficient method of leak checking a charged low- pressure refrigeration unit is to pressurize the system by the use of controlled hot water or heater blankets. When controlled hot water or heater blankets are not feasible, use nitrogen to increase pressure. When pressurizing a system, do not exceed 10 psig.
How is a nitrogen tank used for pressure testing?
To begin testing a component, a nitrogen tank or on-site nitrogen generator will be connected to the component. Nitrogen will be released to elevate the pressure within the test component to a low pressure while forcing any air, debris, or other substances out of the component.
How is a nitrogen leak test carried out?
A nitrogen leak test follows an orderly set of steps which varies depending on the nature of the equipment to be checked. The process typically requires channeling a steady stream of gaseous nitrogen through the selected pipes, vessels, or vats under increasing amounts of pressure.
How is nitrogen used in the petroleum industry?
While best known is its use in the petroleum industry for pressure testing pipelines and containment vessels, nitrogen is also popular for leak testing in a range of other industries. There are several advantages to using nitrogen for leak detection.
What is the purpose of a leak test?
Leak testing is a method of analyzing industrial storage and transport equipment (vessels, tubing, and pipelines) for defects. Leak testing is done to ensure that newly installed systems can withstand the temperatures and pressures associated with normal operations.
Related
This website requires certain cookies to work and uses other cookies to help you have the best experience. By visiting this website, certain cookies have already been set, which you may delete and block. By closing this message or continuing to use our site, you agree to the use of cookies. Visit our updated privacy and cookie policy to learn more.
This Website Uses Cookies
By closing this message or continuing to use our site, you agree to our cookie policy. Learn More This website requires certain cookies to work and uses other cookies to help you have the best experience. By visiting this website, certain cookies have already been set, which you may delete and block. By closing this message or continuing to use our site, you agree to the use of cookies. Visit our updated privacy and cookie policy to learn more.
The regulations for F-gas chiller leak testing have been devised to reduce the environmental impact of HFC refrigerants. They are standardised regulations which are implemented across Europe. Now that we have left the EU, we will continue to be aligned with these regulations.
News Article No.14
Leak Test Frequency Required
The frequency of leak tests depends on the type and quantity of the refrigerant. For example, a system which runs on R134a, the frequency is:
• once every 12 months for a charge less than 3.5 kg.
• once every 6 months for a charge less than 35 kg.
• once every 3 months for a charge less than 350 kg.
All of our maintenance schedules far exceed these minimum requirements. This is because our customers require maintenance visits more often to ensure the efficient running of their plant.
Static Leak Detectors
These leak detectors must be fitted to systems with more than 500 tonnes of CO2 equivalent. For the refrigerants most commonly used in chillers this is:
• R410a 239 kg
• R407c 282 kg
• R134a 350 kg
Global Warming Potential
The GWP numbers below represent the amount of greenhouse effect each refrigerant has, by comparison with an equal mass of carbon dioxide:
• R410a 2,088
• R407c 1,732
• R134a 1,300
Now we have had a look at some of the regulations, let’s have a look at a day in the life of our engineers here at Maximus Chillers. Read below for three different examples of leak testing carried out in the field…
0161 370 7193
✎Contact Form
Pressure Testing following a Leak
In the photo a leak has just been brazed on the condenser. It is recommended in the industry to use a steel braided line with a ¼ turn valve. This is so that if a nitrogen regulator malfunctions, it can be valved off, instead of a system being filled with bottle pressure from the cylinder. For a small system, this could cause a catastrophic explosion. We decided, therefore, to use a small cylinder which would expand into the large volume of the chiller. Should this fault occur, the safe working pressure would not be exceeded. This was taken into account when writing our Risk Assessment Method Statement. The pressure was built up in stages until the test pressure was achieved. This was recorded on our Pressure Test Certificate and witnessed by the customer. The result of the pressure test 4 hrs later was satisfactory and also witnessed by the customer.
Follow up Actions
A return visit was arranged 2 weeks later to leak test the chiller again. Our engineer carried out a visual inspection of all of the parts of the refrigerant pipework. He then used an electronic leak detector to see if it went into alarm. All was okay, so he completed the F-gas Certificate and left it in the customer’s file.
Routine F-gas Chiller Leak Testing during Maintenance
On another site, we look after 6 air cooled MW chillers in a row outside a building at a petrochemical facility. Our engineer ran the systems up, one at a time, to 100% so as to show up any refrigerant shortages. He was looking at the subcooling and superheat values. Two of the systems had poor readings which alerted his attention to a potential leak. On one of the systems, the poor readings were found to be caused by a faulty expansion valve. On the other, he diagnosed that the chiller was running short of refrigerant. He then carried out an inspection and found signs of a leak on a liquid pipe, just after the filter/ drier. The system was locked off with the refrigerant valves closed either side of the leak. This was to prevent the refrigerant from carrying on leaking to atmosphere. Then, he sent a report into Head Office detailing the estimated refrigerant addition needed to replace the refrigerant lost. Refrigerant removal was not needed as the area of the leak had been valved off from the rest of the system. He also detailed the materials required for the job and the necessary labour time that would be needed.
0161 370 7193
✎Contact Form
Looking for a Leak
There are a variety of methods that can be used to identify the location of a refrigerant leak. Here are some examples…
Ultrasonic F-gas Chiller Leak Testing
An ultrasonic leak detector uses a microphone on the end of a wand. This is connected to a battery and processing pack, which is where headphones are plugged into. The sensitivity can be adjusted on the processing pack until a good working level is found. The various components on the chiller can then be inspected to find an audible sound of a leak.
Electronic F-gas Chiller Leak Testing
Otherwise known as a sniff tester, the electronic leak detector is one of the most popular types of leak detectors. The battery can be recharged via the cigar lighter in a car, or can be recharged back at the office with a transformer plugged into the mains. The heated diode sensor and the filter can fail or need to be replaced, so replacement parts are available. The instrument needs to be calibrated to a no refrigerant atmosphere, then it takes samples of the atmosphere being tested. It compares the two atmospheres and looks for a difference. Most electronic leak detectors work with all HFC refrigerants.
Bubble Up F-gas Chiller Leak Testing
There are a variety of bubble up leak detection sprays that are available off the shelf. At Maximus Chillers we make our own leak detection solution in our laboratory at Head Office. We mix two chemicals together in the correct proportions. This solution is carried in sprayer bottles in the boot of each of our company vehicles. When looking for a leak, our engineers use it around the suspected areas of a leak. It is the best form of leak detection that we know, as it can find the smallest of leaks, right up to large leaks which are audible to the ear.
Related Articles:
Chilling Plant Service
Chilled Water System EEV Service
Water System Service of Evaporator
HFC Chiller Service
Process Chiller Vacuum Service
Chiller Breakdown
Chiller Fault Finding & Diagnosis
Chiller Commissioning
Air Cooled Chiller Condenser Testing
Chiller Call Out
Process Chiller Repair Service
Industrial Chiller Repair Service
To read more about the f-gas chiller leak testing procedure hit the Tag at the top of the page.
Read more about checking F-gas equipment for leaks on the Government website