A small question regarding PLAN21+53B
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For example, normally with PLAN21+52, 21 refers to flushing the first-stage mechanical seal, while 52 refers to flushing the second-stage mechanical seal. But if it is 53B and a double-faced mechanical seal is used, then does PLAN21 still have any meaning in this case? Since, structurally, there is only one moving ring, and it is located in the secondary sealing chamber, PLAN21 actually only serves to flush the back part of the impeller and the shaft sleeve; so is it still necessary? Welcome, everyone, to engage in active discussions. See you at 21+53B, everyone: lol
The 21+53B seal adopts a series configuration, with the 21 component primarily serving to reduce temperature. The individual 53B units are arranged in a back-to-back or face-to-face configuration. It depends on the specific operating conditions; every flushing scheme has its own reason for existing.
3CW-FB\3CW-FF\3CW-BB.
The image can’t be uploaded; it uses a face-to-face installation method with a moving ring in the middle. Plan 21 is useful to some extent, as it only allows for the flushing of the back part of the impeller and the shaft sleeve. If two single-face mechanical seals are used (Plan 52) and installed face-to-back, then Plan 21 enables flushing of the first moving ring as well. At present, Plan 21 does help to reduce the temperature of the shaft sleeve and the impeller to a certain extent. But since it is essentially a sealing-flushing method, it is useful yet not very effective, could one say that?
Cool the back side of the mechanical seal, just like with PLAN62, by cooling the back side of the seal
21+53B is 3CW-FF; it’s a very classic design. It’s not true as the original poster said that 21 is useless – the 21 scheme is used to cool the sealing surface at the medium side
I understand what the poster means; it’s saying that the 53B already comes with a heat exchanger, so it’s already cooled down, right?
Can the temperature of the fluid at the outlet of the heat exchanger be used as the inlet fluid temperature for P53B?
The flushing scheme mentioned by the poster is suitable for double-end face mechanical seals, which presumably have two sets of rotating and stationary rings. The 21 serves as the primary seal, helping to reduce the temperature in the sealing chamber as well as cooling the rotating and stationary rings at the medium side, while the 53B acts as a secondary seal. Its purpose is to prevent the medium from leaking out into the surrounding environment in case the seal at the medium side fails. 2. Cool the stationary and rotating rings on the atmospheric side.
First of all, it is important to understand that the friction pairs in each sealed chamber need to be flushed and cooled. Therefore, if the sealing is arranged in a series configuration to divide the dual seal into two sealing chambers, then two sets of flushing are required, such as 11+52 ； 11+53 ； 21+53, etc. If it is sealed within a sealed chamber, it is a separate 54,53 ； Secondly, the significance of the series sealing: if the first seal fails and leakage occurs, the subsequent seal can still keep functioning for 8 hours! It can alert the customer to a damaged seal and switch to a backup pump within 8 hours!