Leakage in the mechanical seal of IH pumps
Thread Content
IH-type pump, equipped with double-end face mechanical seals; feed is introduced at the pump inlet in reverse flow, with a liquid injection pressure of about 1 kilogram. Without cooling water for the seal, opening the pump inlet valve to feed fluid causes the seal to be pushed apart, resulting in leakage ； First, turn on the cooling water for the mechanical seal, then open the pump inlet valve to feed material. After starting the pump, leakage occurs at the mechanical seal, and the material leaks into the cooling water for that seal. The manufacturer said it was a problem with the pump cover and insisted on replacing it. I wonder if it makes sense? Some expert friend, please give some advice. Thank you.
I don’t know much about double-sided machine seals; based on the description, it seems that the spring force of the seal is not sufficient
The seal cooling of the pump and the material flow are two separate systems; if material leaks into the seal cooling water, it indicates a leak in the walls of the cooling system. When the cooling water for the seal is not turned on, opening the pump inlet valve to feed fluid will cause the seal to be pushed aside and leak; this indicates a problem with the installation of the seal, as its spring is somewhat loose.
How should this question be phrased? You say there’s a problem with the mechanical seal? That’s also fine. You say the issue of sequence of operations is also okay. In simple terms, if you do not use seal fluid pressure and simply pour the fluid in, it will definitely push the stationary ring at one end of the mechanical seal away. If that stationary ring is not reset in time, it may lead to leakage of the medium into the seal fluid when the machine is started. However, if hydraulic pressure is used, it must be higher than the pressure used for pouring the fluid in. Otherwise, change the machine seal structure.
Is the mechanical seal static ring installed on the pump cover? In this case, the axial position of the static ring is changed, thereby achieving the compression amount specified in the design of the mechanical seal
It is recommended to turn on the cooling water first, then start the machine, and finally open the valve to test it; if leakage persists, it is likely that the spring of the mechanical seal lacks stiffness!
This is caused by insufficient compression of the mechanical seal; we have encountered similar situations on site as well. The solution was to add shims behind the stationary ring in order to increase the compression of the mechanical seal.
The situation on site is that there is no leakage during static pressure testing, and the inlet valve also shows no leakage; however, leakage starts to occur once the system is turned on and in operation.