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How Bottom Blowdowns Work With Miura Boilers


To keep a Miura boiler running for as long as possible at optimal levels, there are a number of maintenance chores that must be performed every now and then. One such piece of upkeep is called a bottom blowdown. This is something that must be done intermittently in order to remove particles, sludge, and any other type of sediments that may have settled at the bottom of the boiler and started to accumulate in the piping.

One of the benefits of a Miura boiler is that the BL controller will let you know when it’s time to perform a bottom blowdown. When it’s time to perform the bottom blowdown, it’s sometimes wise to allow the pressure inside your boiler to drop below 30 PSI. However, this step can sometimes be optional. As long as the piping for your bottom blowdown is secure, you can perform the blowdown at full pressure. Just keep in mind that you also have to follow any local codes or regulations that may exist in your area before starting the bottom blowdown.

Also, before starting this process, it’s important to be aware of your equipment. Every Miura boiler has one fast-opening blowdown valve. Some models will also have a second slow-opening blowdown valve. This second valve is required for boilers that have a maximum pressure that exceeds over 100 PSI. If this describes your boiler, make sure you note the position of both valves.

The fast-opening valve is what isolates the blowdown piping so you can dispose of the sediment that has built up over time. The second valve, if it’s there, is for safety purposes. It will help to start and stop the flow during the procedure, reducing the risk of water hammer in the piping.

Once you’re ready to perform the bottom blowdown, the first step is to turn off the operational switch on your Miura boiler. You also have the option of closing the main steam vale. The next step is to slowly open the fast-opening valve and then do the same for the second valve. Doing this will drain the boiler of any particles or sludge. You will want to keep the valves open until the flashing B on your Miura boiler’s control panel disappears. Once the water level drops below the conductivity probe, the flashing B should disappear to confirm that the blowdown is complete.

Once the flashing B is gone, you can close the valves in the reverse order in which they were opened. That means the slow-moving valve should be closed first and then the fast-moving valve. If the valves aren’t left open long enough, the flashing B won’t disappear, letting you know that the blowdown is still necessary. Of course, if the vales are open too long, you risk draining too much water from your boiler. When your boiler is refilled, it could experience a low pH, making it vulnerable to corrosion.

Once you have confirmed that the process is complete and closed the valves, the main steam valve can be opened. Then you can turn the operational switch on your boiler on again and resume normal operations. As long as you follow these steps, performing a bottom blowdown on your Miura boiler can be done without any hassle.