We have had a high failure rate of sewage pump seals in a fairly new installation, which then leaks black water into the motor bearing with predictable results. The pump model is UNIVERS-A by Herborner. There are a number of system issues I believe are contributing to the failure rate, but...
We procure pumps for our customer with casings made of CA6NM, similar to 400-series stainless steel that develops a thin rust layer on as-cast surfaces. Our customer objects to the rusty look, but would also like to avoid the lifetime maintenance burden of painting the pumps.
My understanding...
We have a system that generates chlorine from the salt in sea water as a biofouling control in a condenser. We have a problem with hydrogen gas by-product collecting in un-ventable high points in the system, such as inside a plate-and-frame heat exchanger. Is there a chemical that could be...
I have a question about an orifice flowmeter installation being used to verify a pump is putting out its design flow and head. It has a 2.68" orifice in a 4" pipe, with 58" of straight pipe upstream and 15.75" straight pipe downstream. The question deals with the first downstream fitting: a...
The pump is a horizonally mounted, closed impeeler, single stage, end suction dual volute, top centerline discharge centrifugal pump, 1800 RPM, 12" suction and discharge.
The service is a chilled water pump that circulates cold water from an AC plant. It initially runs with no mechanical seal...
I'm having trouble understanding the wick lubrication feature in a large horizontal electric motor. The bearing housings at each end contain an oil sump where, when level, the balls roll through a shallow depth of oil. An oil wick is also installed that leads from the bottom of the oil sump to...
I'm in the middle of a dispute regarding the corrosion resistant nature of CA-6NM. A specification says that external surfaces of corrosion resistant parts shall not be painted, referring to a note that defines (for the purposes of this spec) what materials are considered to be corrosion...
I frequently see a maximum allowed oil temperature of 194F (90C) in machine bearing applications. I know the oil life decreases rapidly at higher temperature due to oxidation, but what is the basis of the 194F limit? So many hours of life?
Also, in a ball bearing, is there any known...
We use Mil-Spec grade 2190-TEP lubricating oil in numerous machinery bearing applications. I've heard a general "rule of thumb" that the service life of this oil is halved for every 18 to 20 degrees above 150 degrees F. Does anyone know of any test data or other more formal information that...
I'm working with a pump manufacturer on a new design that is experiencing excessive thrust bearing temperatures. We know part of the problem is higher than designed-for thrust load, but the magnitude of the thrust doesn't seem to completely account for the temperature rise. This design employs...
I have an application where I want to use a carbon steel (SAE J429) grade 8 stud to hold a piece of equipment to its foundation. It is a 1.125" stud that will be torqued to 650-700 ft-lbs. I'm hearing there is some concern about some kind of stress corrosion cracking or hydrogen embrittlement...
We have a requirement that certain castings be heat treated in a vacuum and/or inert gas atmosphere furnace. However, one casting is too large for the supplier's atmosphere controlled furnace, and is proposing to use a propane fired furnace instead, stating that this is effective at avoiding...
I need to size a steam blowdown line to vent a pressure vessel initially at 100 psig. The flow will be initiated by opening a butterfly valve in the line near the pressure vessel. The blowdown line will be on the order of 10 to 15 feet long, then dump into a 36" duct. The backpressure at this...
