Many new self-contained fractional horsepower refrigeration systems will be shipped from the factory with no service access ports. These systems will typically have a ¼-inch section of process tubing on both the high and low side that is pinched at its end. This will enable a technician to add an access port, if needed in the future, to measure the system’s pressure and to add or remove refrigerant from the system.
Many technicians will add some type of saddle valve to initially pierce the system and then either replace the saddle valve with a brazed Schrader valve or leave the saddle valve on the system. When the saddle is left on the system, there is a possibility for it to leak over time. They do not always leak, but the possibility does exist. However, to braze in a Schrader valve, some technicians will recover the refrigerant, braze in the new valve, evacuate the system, and add the refrigerant back into the system.
Occasionally after adding a saddle valve to the system, you will discover that you do not need to recover the refrigerant to make the necessary repairs, so moving the saddle valve will require extra work that may not be needed. If you elect to remove the saddle valve, one option available that would not require the recovery of the refrigerant is to simply pinch off the tubing before the saddle valve, cut out the saddle, and braze the end closed. However, if you do this, you will need to add another saddle valve back on the system if you need to once again measure the system’s pressure or add or remove refrigerant from the system.
If you want to leave an access valve on the system and you are concerned about a saddle valve leaking over time, you can directly add a Schrader valve to the system without recovering the refrigerant with the use of a pinch-off tool. Using this tool, you can isolate the pinched end of the process tube from the refrigerant in the system, then cut out the pinched end, braze in a new Schrader valve, and use the pinch-off tool to re-round the pinched section. This allows the system pressure to be exposed to the Schrader valve. You will need to remove the small amount of air from the small section of tubing between the pinch and the new Schrader valve before you re-round the pinched tubing. You can either push the air out the Schrader valve as you re-round the tubing or run a vacuum pump on the small section of tubing.
It does take a little more time to initially add a Schrader valve to a new system instead of initially installing a saddle valve, but it is definitely a procedure that will ensure a leak-free system. And with the use of a pinch-off tool, you will not need to recover the refrigerant. It might take a little practice to effectively use the pinch-off tool. I would recommend practicing at your shop if you have never performed this procedure before doing it on a customer’s system. Once you do it once or twice, you will become quite efficient at the process.
