Hi all,
I am hoping that someone can help me. I apologize in advance for this very lengthy post.
We installed a bag filter system for our heated, 600 gallon alkaline degreaser tank and it has been nothing but a nightmare since. The rep we purchased the system from is not sure why we are having so many problems. He did come to our facility to look at the application before quoting the system.
The degreaser tank is used to clean oils, grinding dust, and other debris off from small springs and stampings. The oils are standard non-chlorinated lubricating/stamping oils. We clean both carbon and stainless steel parts in the tank. The raw degreaser is a powder that we mix with water and is heated to 175 F. We keep it at an 8 – 12 oz/gallon concentration; the pH runs just over 12.5. The components, CAS Numbers, and concentrations of the raw degreaser are:
Sodium Hydroxide, 1310-73-2, 10-30 %
Sodium Carbonate, 497-19-8, 40-70 %
Alcohol Ethoxylate Phosphate, 68130-47-2, .5–1.5 %
Sodium Tripolyphosphate, 7758-29-4, 3–7 %
Nonylphenoxpoly (Ethyleneoxy) Ethanol, 9016-45-9, 1–5 %
The filter is a basic, out of tank bag style filter using a centrifugal pump with a 3 hp 3500 RPM motor. The pump has a standard John Crane Type 21 mechanical Seal with carbon/silicon-carbide faces, viton elastomers, and 316 stainless metal parts. The pump is located about 8 feet from the tank.
After running only a couple of weeks, a leak developed between the motor and pump. We took it apart and found that the seal had too much wear (wouldn’t fit tight on the motor shaft). Our distributor said we must have run it dry. I said I didn’t think so, but he disagreed.
We replaced the seal and this time it lasted less than one week. Leaks developed at two of the brass ball valves and at the pump again. We were sure that the pump had not been run dry this time. The pump seal was worn again so we replaced it a second time. The ball valves showed significant damage. They looked like they were attacked by termites. Each of them had one or more tunnel like grooves dug into them. We replaced all the brass ball valves (which the rep said would be fine to use) with stainless steel valves. The piping was already stainless.
Less than two weeks later, it suffered a major failure. At some point the pump began leaking badly and, before anyone caught it, all of the liquid from the tank had leaked into a pit behind the tank. OK, so this time the pump did run dry, but the seal had failed first. We not only had to replace the seal, we also had to purchase a new motor because the seal wore a .015 deep x .10 wide groove in the motor shaft.
Keep in mind that all this time we are communicating between the system rep, the pump manufacturer, and the chemical supplier to try and solve the problem. All I kept hearing from everyone was the proverbial “huh, I never heard of that before”. Everyone seems to agree that the degreaser we use should be compatible with the wetted parts.
The rep insisted that we were doing something that caused the problem. Either we were running it dry or someone was putting something in the tank that caused damage to the seal. They said they have these pumps everywhere with no problems.
OK, once more we put a new seal on the new motor shaft. It lasted almost two weeks. Took it apart – the seal spring was broke in three places and the motor shaft again has a groove wore in it.
The rep now says that the problem must be that we should have used a carbon seal instead of the silicon-carbide seal. He explained that a straight carbon seal is more forgiving. I reminded him of the groove in the motor shaft and told him that I was not going to purchase another motor just so “we could try a different seal”. He told us that “that little groove” would not matter with a new seal. I disagreed but just to prove a point, we went ahead and put the new seal in, re-installed the pump, turned it on and watched the liquid immediately begin to leak out onto the floor.
I have questioned using this type of pump for the application numerous times starting after the first failure but the rep insists that this is the correct pump for the application and that it is something we are doing.
What do you think?
I am hoping that someone can help me. I apologize in advance for this very lengthy post.
We installed a bag filter system for our heated, 600 gallon alkaline degreaser tank and it has been nothing but a nightmare since. The rep we purchased the system from is not sure why we are having so many problems. He did come to our facility to look at the application before quoting the system.
The degreaser tank is used to clean oils, grinding dust, and other debris off from small springs and stampings. The oils are standard non-chlorinated lubricating/stamping oils. We clean both carbon and stainless steel parts in the tank. The raw degreaser is a powder that we mix with water and is heated to 175 F. We keep it at an 8 – 12 oz/gallon concentration; the pH runs just over 12.5. The components, CAS Numbers, and concentrations of the raw degreaser are:
Sodium Hydroxide, 1310-73-2, 10-30 %
Sodium Carbonate, 497-19-8, 40-70 %
Alcohol Ethoxylate Phosphate, 68130-47-2, .5–1.5 %
Sodium Tripolyphosphate, 7758-29-4, 3–7 %
Nonylphenoxpoly (Ethyleneoxy) Ethanol, 9016-45-9, 1–5 %
The filter is a basic, out of tank bag style filter using a centrifugal pump with a 3 hp 3500 RPM motor. The pump has a standard John Crane Type 21 mechanical Seal with carbon/silicon-carbide faces, viton elastomers, and 316 stainless metal parts. The pump is located about 8 feet from the tank.
After running only a couple of weeks, a leak developed between the motor and pump. We took it apart and found that the seal had too much wear (wouldn’t fit tight on the motor shaft). Our distributor said we must have run it dry. I said I didn’t think so, but he disagreed.
We replaced the seal and this time it lasted less than one week. Leaks developed at two of the brass ball valves and at the pump again. We were sure that the pump had not been run dry this time. The pump seal was worn again so we replaced it a second time. The ball valves showed significant damage. They looked like they were attacked by termites. Each of them had one or more tunnel like grooves dug into them. We replaced all the brass ball valves (which the rep said would be fine to use) with stainless steel valves. The piping was already stainless.
Less than two weeks later, it suffered a major failure. At some point the pump began leaking badly and, before anyone caught it, all of the liquid from the tank had leaked into a pit behind the tank. OK, so this time the pump did run dry, but the seal had failed first. We not only had to replace the seal, we also had to purchase a new motor because the seal wore a .015 deep x .10 wide groove in the motor shaft.
Keep in mind that all this time we are communicating between the system rep, the pump manufacturer, and the chemical supplier to try and solve the problem. All I kept hearing from everyone was the proverbial “huh, I never heard of that before”. Everyone seems to agree that the degreaser we use should be compatible with the wetted parts.
The rep insisted that we were doing something that caused the problem. Either we were running it dry or someone was putting something in the tank that caused damage to the seal. They said they have these pumps everywhere with no problems.
OK, once more we put a new seal on the new motor shaft. It lasted almost two weeks. Took it apart – the seal spring was broke in three places and the motor shaft again has a groove wore in it.
The rep now says that the problem must be that we should have used a carbon seal instead of the silicon-carbide seal. He explained that a straight carbon seal is more forgiving. I reminded him of the groove in the motor shaft and told him that I was not going to purchase another motor just so “we could try a different seal”. He told us that “that little groove” would not matter with a new seal. I disagreed but just to prove a point, we went ahead and put the new seal in, re-installed the pump, turned it on and watched the liquid immediately begin to leak out onto the floor.
I have questioned using this type of pump for the application numerous times starting after the first failure but the rep insists that this is the correct pump for the application and that it is something we are doing.
What do you think?
