Advantages 1 solids are removed from the flush stream

This preview shows page 21 - 23 out of 56 pages.

Advantages 1. Solids are removed from the flush stream keeping the seal clean. 2. Unlike a strainer or filter, the abrasive separator does not have to be cleaned. Disadvantages 1. It is sometimes difficult to obtain the desired pressure differential required for the abrasive separator to operate efficiently. Exceeding the published differential pressure will cause the separator to not function properly. 2. Improper piping will cause the separator to not operate efficiently. Unless the pressure differential from the two discharges to the final sources are almost the same, the separator can either starve the seal or allow abrasives to flow into the chamber. 3. The abrasive separator and the piping in the dirty outlet leg can become worn over time from the abrasives spiraling down the coned shaped bore. 4. Not advisable on low vapor margin applications as vapor bubbles have a more natural inclination to be channeled into the seal flush connection. Sizing Generally the flush rate sizing will be the same as a Plan 11. Various models or sizes of separators are available to provide different flow rates depending upon the pressure differential available. Controlling The flow rate can be controlled by an orifice in the line running from the pump discharge to the inlet of the abrasive separator. This orifice should not be less than 1/8 inch (3 mm) and should usually be larger depending upon the size and the concentration of the particles being removed. Either multiple orifices or a PLAN 31 V F Q/D From pump discharge To pump suction Figure 9 - Seal Flush Plan 31 SEAL CHAMBER FOR PLAN 31
Image of page 21

Subscribe to view the full document.

20 Circulation Systems "choke tube" can be used to control the flow. On vertical pumps where the seal chamber is at discharge pressure, a separate line needs to be added going from the bushing at the bottom of the seal chamber back to suction to reduce seal chamber pressure to allow the clean fluid to enter the seal cavity. On small or low differential pumps no orifices are required. It is important that the lines running from the clean outlet at top of the separator and the dirty outlet at the bottom be at similar pressures to obtain proper separation and flow rates. It may be necessary to vary the length of tubing or piping in one or both discharge lines to get the proper flow established. General The proper installation of the abrasive separator is a necessity for this flush plan to work. Typically the separator needs to have a minimum of a 15 psi (1 bar) differential to operate properly. The maximum pressure should not exceed the published differential pressure limits of the abrasive separator, typically 160 to 200 psi (11 to 13.8 bar). The maximum particle size should be less than ¼ the size of the inlet orifice. Also to operate properly, the system should be vented. If air is trapped in the top of the separator, it will not work. To vent the system, use a tee fitting at the clean outlet at the top of the separator. From the tee fitting, go to the seal chamber. Off the side of the tee fitting use a valve to vent off any trapped air.
Image of page 22
Image of page 23

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern