A feature on many Cornell clear liquid pumps, an external hydraulic balance line, allows better performance, without having to drill holes in impellers. The following copy comes from Cornell Pump’s Hydraulic Seminar Workbook—lasted updated in 2019.
THE EXTERNAL HYDRAULIC BALANCE LINE
To lower pressure in the stuffing box (or seal chamber) and to attempt to limit the inherent axial force created by the impeller, traditional centrifugal pump designs use large holes bored through the impeller. Cornell has a more effective method –THE EXTERNAL HYDRAULIC BALANCE LINE.
High pressure liquid from the volute passes through the hub ring clearances into the cavity between the stuffing box and the impeller. Liquid returns via the balance line to the region of lower pressure at the pump inlet, taking with it any sand or silt that may otherwise build up at the stuffing box. This method reduces turbulence, improves hydraulic efficiency, increases the life of packing, mechanical seals, and bearings – provides positive control of axial forces. It also reduces wear because sand is not trapped behind the impeller, near the shaft.
Included in the Cornell Virtual Pump School packet:
Installation and Care workbook: shows procedures on how to properly install a pump and keep it running effectively.
Pump Seminar workbook: provides formulas and explanations of pump hydraulics.
Condensed Hydraulic Databook: A pocket-sized resource for calculating friction loss.
Various brochures: showing in detail some of the innovations of Cornell Pump, such as Co-Pilot pump monitoring system.
Assembly reference materials: for reference during the pump build session.
Cornell fidget spinner: helps keep focus, and has a bottle opener for a networking event libation.
MagLite® Flashlight: Branded with Cornell Co-Pilot, this premium can help light your way to great learning, or at least assist you when inspecting a pump.
USB Drive: Contains presentations that we will be discussing during the classes. We hope this makes note taking and following along easier.
These packets are being sent to registrants so they can prepare for Cornell Pump’s Virtual Pump School on September 15 through 17, 2020. They have already reserved their packet—and you can too. Learn more about Virtual Pump School, and register online.
Virtual Pump School is just $79USD for three great days of learning, resources, and networking—plus you can re-watch the classes for a month afterwards. Sign up now!
Making the right pump selection is very important; the right choice can reduce energy costs and provide decades of strong service. The wrong choice could dramatically increase operation and maintenance costs, and limit the life of the pump.
This reminder of what to check comes from Cornell Pump’s Hydraulic Seminar workbook. The information is a reminder of lessons about calculating Total Dynamic Head (TDH). Participants at Cornell’s Virtual Pump School 2020, will not only get this handy workbook, but also get numerous presentations (e.g. NPSH, TDH, pump sizing, etc.) that lead to this very topic (Pump Selection) being covered in detail on day three of the school. Plus, you’ll get the Condensed Hydraulic Databook, along with many other reference materials.
Right now, cost for general admission to the school is only $79 USD. But hurry – It goes up to $99 this weekend. Learn more about Virtual Pump School 2020. The school runs September 15 through 17, 2020, with ten sessions total offered per day; five each in Basic and Advanced tracks.
How To Select a Centrifugal Pump
The pump is selected after all the system data has been gathered and computed. The system TOTAL CAPACITY in gallons per minute and TOTAL DYNAMIC HEAD in feet must be determined. You should consider suction submergence, NPSHr and NPSHa, various speeds, other drives (engine, motor, etc.) and all system conditions to optimize the selection.
Typical Pump Installation
TOTAL DYNAMIC HEAD is the SUM of the following:
Suction pipe friction (see Condensed Hydraulic Data Book).
Suction lift (vertical distance, in feet, from lowest expected water surface to center of pump inlet).
Suction entrance loss (usually figured at one velocity head plus foot valve losses
Discharge pipe friction (Condensed Hydraulic Data Book).
Discharge lift (vertical distance, in feet from pump to high point in system).
Pressure, in feet, for service intended (pressure, in P.S.I., x 2.31 equals feet of head).
Miscellaneous losses, in feet (for valves, elbow, and all other fittings, see Condensed Hydraulic Data Book).
For capacity of 320 GPM, total head in feet is determined as follows:
28’ Suction friction (6” steel pipe, 20’ long – 1.39’/c x 20’)
5’ Suction lift
3’ est. Suction entrance loss (1’ vel. Head + 0.49’ + screen loss)
14’ Discharge friction (6” steel pipe,1000’ long – 1.39’/c x 1000’)
15’ Discharge lift
100’ System pressure (43 P.S.I. x 2.31)
10’ Miscellaneous losses (Use your own safety factor here)
147’ total head (Approx.)
For capacity of 600 GPM, total head in feet is determined as follows:
.89’ Suction friction (6” steel pipe, 20’ long – 4.46’/c x 20’)
5’ Suction lift
5’ est. Suction entrance loss (1’ vel. Head + 1.6’ + screen loss)
Cornell Pump’s design for double volutes can help keep radial forces from snapping a shaft, while increasing wear life.
The Double Volute System enables Cornell single stage, end-suction centrifugal pumps to easily handle large volume and high-pressure jobs.
As the impeller adds energy to the fluids, pressure increases around the periphery of the volute. On single volute pumps, the increasing pressure acts against the impeller area and creates unbalanced radial forces. By contrast, the Double Volute System effectively balances these forces around the impeller to reduce shaft flexure and fatigue.
Cornell’s “DVS” design helps keep shafts from breaking, extends the life of packing and mechanical seals, wear rings, and bearings – maintaining high hydraulic efficiency.
This diagram comes from page 3 of Cornell’s Hydraulic & PumpsSeminar workbook, which will feature prominently at our Virtual Pump School. Every attendee gets a print copy of the book, along with other printed materials, and even a Maglite® flashlight. Sign up now—the regular rate ends soon! Only $79 for three great days of learning, resources, and networking!
Cornell is excited to announce the winners of our 5K followers drawing!
When we hit 5,000 followers on LinkedIn, we told those that had followed us, and any that followed us with the next week, they would be entered into a drawing for some Cornell swag. The prizes and winners include:
Cornell Yeti Rambler
Kevin Paczwa at Rexnard Corporation
Daniel Trujillo at Rain for Rent
Cornell MagLite Flashlight and Leatherman Knife Combo
Shelley Hadaway at RWN Pump and Fabrication
Rod Smith, CPA, CMA at Ship Repair and Construction
Cornell North Face Jacket
Michael Hill at Sunbelt Rentals
Richard Hurst at Cargill
And you can get a Cornell MagLite flashlight if you attend our virtual pump school. As part of the mailed packet, we’ll send you a flashlight! Register for Virtual Pump School now – early bird pricing ends on August 15!
Hundreds of people have taken advantage of the early-bird pricing on virtual pump school. At $59 for three days of classes, that is less than $4.00 an hour for industry-leading instruction!
But, the early-bird pricing is ending on Saturday, August 15. Register now for the lowest price.
Virtual Pump School runs Tuesday, September 15 through Thursday, September 17, 2020. Classes are live from 8:30 a.m. until 1:20 P.M. PDT, run 50 minutes, and include a short break between sessions. Extensive daily agenda and class choices are available on the registration website.
The Cornell 2020 Virtual Pump School has two tracks, a basic track and an advanced track, and over 26 different subjects, so the school is applicable for both those new to the pump industry, as well as seasoned pump professionals.
The early-bird registration special of $59 gets you access to all three days of live seminars, the mailed packet, and to the recorded sessions afterward. Attendees also receive a certificate of attendance, and corresponding hours engaged for CEU/TCU credits after the school is finished. Sign up now , the early bird pricing ends on Saturday!
Packing is often used as a sealing method for general purpose and agricultural pumps. For the packing to be effective, and not be overheated by the shaft rotation, there must be a consistent drip of liquid, about one drip per second.
Running clearance on most new general purpose water pumps is about .010 inch on a side. (check with the factory for specifications on for your model). If wear increases this to .032 inch, the wear ring should be replaced and the impeller repaired or replaced. Wear may be caused by abrasives in the pumpage, unsupported piping loads, or other causes.
Tighten the gland nuts 1/4 turn every ten minutes until a leakage of only 40–60 drops per minutes is achieved. If the packing must be replaced, a packing puller may be needed.
The diagram is from Cornell Pump’s Installation and Care book; a workbook that provides great ideas and reminders for pump set-up and operation. Every registrant to our Virtual Pump School will not only get this workbook, but also our Pump Seminar workbook and Condensed Hydraulic Data Book, along with (most importantly) more than 15 hours of pump and hydraulic instruction. Learn more about Virtual Pump School.
Cornell has been innovative and efficient for nearly 75 years. This page from one of our brochures, circa 1955, shows off a feature you still find on our pumps; the ability to mount in many different configurations. Cutting edge in the 50’s, it still gives our customers the flexibility to use our pumps in a multitude of ways.