NPSHr

Net Positive Suction Head Required

All pumps have requirements to their performance, and no pump can perform well if you can't meet it's needs.

Below is part of the Cornell® 6NHTB-19 Pump Curve with a colored over-lay for this discussion.

NPSH REQUIRED is found at the top of the curves in FT.

What does this mean?

For this pump, running at 2100 RPM with its horsepower requirements met, you can pick a flow rate and easily find its NPSH REQUIRED.

1500 GPM = 5.5 FT.
2000 GPM = 8 FT.
2500 GPM = 11 FT.
3000 GPM = 17 FT.

Net Positive Suction Head Required is the required feet of head going into the back of the pump for it to function properly and achieve your desired flow rate.

Easy signs your pump's NPSHR is NOT met: 

• The pump is shaking
• It sounds like you have rocks going through your pump
• Gauges and Valves are falling off
• The unit is vibrating
• The tongue's jack is sunken into the ground from vibration
• Your gauges are broken
• Your suction cover shows physical damage of gouging and wash-out
• Your impeller shows physical damage of gouging and wash-out

CAUTION! Your Pump is Cavitating! 
More about cavitation: http://www.engineersedge.com/pumps/cavitation.htm



MEETING NPSH REQUIRED AT THE SITE:

Atmospheric Pressure – Friction Loss in Intake Hose – NPSHr of Pump = Static Suction Lift

• Static Suction Lift tells us the maximum distance from the top of the water to the center of the pump's impeller we can operate within without causing cavitation.  The pump needs to be primed, but not fed with another pump within this distance.
  
• Atmospheric Pressure is the force of air pressing down on a body of water - providing us with free FEET OF HEAD: we will use an easy-to-remember and conservative estimation of 30 FT. for atmospheric pressure.
  
• Friction Loss in Intake Hose is estimated using a C-140 Head Loss Chart.  See Below. We have modified it for 25 FT lengths. example: 10" Hose at 2000 GPM = 0.5 FT
  
  
• NPSHr is found on the pump's curve at a given flow rate. example: 2000 GPM = 8 FT.

30 FT. – 0.5 FT – 8 FT. = 21.5 FT

21.5 FT = the maximum distance from the top of the body of water to the center of the pump impeller that this pump can operate at without being force-fed and without cavitation at 2,000 GPM.  If you drop the flow rate, these numbers change and it has less NPSHr, and more Static Suction Lift

Call or write with Questions!

712-653-3045 - PCE Office

nancypuck@gmail.com - Nancy
bpuck@puckenterprises.com - Ben
jpuck@puckenterprises.com - Jeremy

Jake Pumps 3,000 gallons per minute

This is Jake. After high school he joined the military, fought overseas, and came home to Manning to raise his family. He can fly the United States flag as he'd like, and he certainly makes sure there is one on his tractor. POW on one side, Stars & Stripes on the other.

This fall he's quite consistently pumping over 2,500 gallons per minute. When I took these photos he was right over 3,000 - about 3020 GPM most of the time.

At a local finishing barn, his crew had a Lead Pump at the site, and a booster pump in the field. Both were set up with MobileStar. 

Lead Pump - a 550hp 13.5L John Deere with a 6NHTB-19 Cornell pump using a PCE Self-Prime system.  

Booster Pump - PT 5069 - same engine and pump as the lead.

Mainline Hose: 8 inch

Drag Hose: 6 inch

On the tractor he has a PCE Tractor-Mounted Swing Pipe with a PCE injection bar set up with Dietrich 70 Series Shanks to inject 5-6 inches deep.

This is a PCE text-book turn-around: making a "golf-club" swing, placing the bar back into the ground along the fence line, and slowly turning back to a 45 degree angle across the field. No backing up. 

Pretty....even when covered in Manure.

When it comes to friction loss in hose, it takes 7 lengths* of 8" hose to equal the friction loss in 2 lengths of 6" hose. That friction loss is equal to 0.85 lengths of 5 inch hose.

 *1 length = 660 ft.

***friction loss is still an estimation based on flow through materials similar to hose.

New lead pump

First day out with the new prototype lead pump.  John Deere 9.0 liter with a 6nhtb-19.  PCE fast prime and down riggers to level it out at the site.  Working great so far.

Agitation Boat - Front Cannon!

Last week, I was fortunate enough to travel north with Dad to South Dakota and Minnesota. We visited two pumping sites in South Dakota that were running PCE Agitation Boats on dairy lagoons.

The first dairy we visited was being pumped by Precision Pumping, Inc. of Minnesota.  They have an early model of BOAT 2067 with a Cornell Redi-Prime® Pump. We delivered a front nozzle attachment for the "cannon" - the Gate 3 outflow above water. This outflow can be used to sink solids floating on the top, to wash down the banks, or to deliver fluid through a hose (if the boat is anchored to shore).


Upon arrival at the lagoon, there was 12"-18" of crust on the top of the lagoon, with 2 lagoon pumps agitating - one at each end.

Lagoon Condition BEFORE Boat Agitation

 Over a very short period of time using the front nozzle, the Agitation Boat broke through the thick crust in the center and traveled to the opposite end, where Dad shut down the rear agitation nozzles against the bank, and used the front nozzle under the water to rotate the boat left and right while running the front cannon above the water.  This unit moves about 4,000+ GPM.

Using the Agitation Boat as stationary agitation against a bank

See another video of this at: http://www.malechainc.com/blog.html




With the control to individually open & shut 3 different outflow gates, you have a lot of control over agitation. The gates can be utilized to control the amount of flow through each agitation nozzle by only partially opening or closing a gate. Throughout the video, you can see variations in flow out the front cannon as the other gates are opened or closed.

Pumping!

Jake's leaving to start fall pumping at the dairy. His goal: to see 3,000 GPM through the system with 8 inch hose, 6 inch drags, a SP 5069 prototype lead pump, PT 4069 pumps inline, MobileStar.... a boat... He'll keep us posted.

A Comparison of 3 Pumps

Let's do a comparison of 3 Cornell Pump Curves:

4414 - 4 inch outflow, 4 inch intake, 14 inch impeller

4514 - 4 inch outflow, 5 inch intake, 14 inch impeller

4NHTB - 4 inch outflow, 5 inch intake, 17 inch impeller

I know it's bad to start with a disclaimer, but please realize these numbers are found using WATER, AT SEA LEVEL.  ESTIMATIONS HAVE BEEN MADE. This is simply an exercise in reading pump curves.

 ***NOT GUIDELINES OF HOW TO PLACE PUMPS.***

Below is the curve for the 4414 Pump. Notice the US. GALLONS PER MINUTE across the bottom. The last number listed is 1600 GPM.  Follow the 1600 line straight up, and it says if you run this pump at 2300 RPM, you could achieve 320 FT of TOTAL DYNAMIC HEAD. The pump is running at about 77.5% efficiency way out there in the top right corner (almost the best efficiency this pump can run). But it has to be fed (at an almost impossible amount to be a lead pump at this GPM). The NPSH (net positive suction head) is greater than 24 ft. -- I'm estimating closer to 30 ft. or more to keep it from cavitation.  

On flat terrain, wishing to travel 1 mile, and wishing to use 4414 pumps to get there, we will use 6" mainline hose, with a Head loss at 1600 GPM to be about 90 FT per 660 FT. length of hose.

320ft of TDH leaving pump 1. Pump 2 will need 30 ft NPSH to keep from cavitation. 

320' ÷ 90' (Head loss) = 3.55 lengths of hose

3 lengths x 90' = 270' of TDH used

320' - 270' = 50' of TDH remaining

Pump 1 (with it's NPSH fulfilled), 3 lengths of 6" hose, Pump 2, 3 lengths of 6" hose, Pump 3, you get the idea.

Lets say you drop into 5 inch drags after the last 4414 pump. Head loss jumps to 200' per 660ft length. No NPSH required to the applicator so:

320' ÷ 200' = 1.6 lengths of drags

BELOW -- 4514 Cornell Pump Curve

The top right corner of this curve ends right around 1950 GPM, at 2300 RPM, with about 30' NPSH 

required, providing 290ft. of TDH.

Again - 4514 Pumps in line with 6" mainline hose on flat terrain.

At 1950 GPM - Head loss in 6" hose is about 130' ft.

290' TDH ÷ 130' = 2.23 lengths of hose

2 x 130' = 260' TDH used

290' - 260' = 30 ft. TDH remaining to fulfill NPSH Requirements for the next pump.

SO: Pump 1, 2 lengths of hose, Pump 2, 2 lengths of hose, Pump 3, 2 lengths of hose, Pump 4, 2 lengths of hose -- this is silly...

Lets try this 4514 at 1500 GPM, still 2300 RPM, still in the 72% efficiency with less NPSH Required (19') and more TDH (330 ft). Head loss is less, at 1500 GPM is 80ft.


330' ÷ 80' = 4.125 lengths of hose
4 x 80' = 320' of TDH used
330' - 320' = 10 ft remaining -- NOT ENOUGH - 19 ft is needed for the next unit.


How about 3 lengths?
3 x 80' = 240'
330' - 240' = 90 ft remaining


So: Pump 1, 3 lengths of hose, Pump 2, 3 lengths of hose, Pump 3, 3 lengths of hose....




BELOW: 4NHTB Cornell Pump Curve


With this pump we're going to follow the 1875 GPM line up and meet 2000 RPM and receive 390 ft of TDH. NPSH Required is estimated at about 25' - 27'.

Head loss at this flow through 6" mainline is about 120 ft. So:
390' ÷ 120' = 3.25 lengths
3 x 120 = 360' used
390' - 360' = 30' remaining  (25' to  27' needed)


Head loss through 8" mainline at this rate is about 51 ft.
390' ÷ 51' = 7.647 lengths
7 x 51' = 357' used
390' - 357' = 33' remaining (25' to  27' needed)


6" hose:
Pump 1, 3 lengths of hose, Pump 2, 3 lengths of hose, Pump 3,
**Head loss through 5" drags at 1875 GPM is about 285 ft.  - giving you 1.368 lengths to the tractor


8" hose:
Pump 1, 7 lengths of hose, Pump 2, 3 lengths of 6" - mainline/drags


Theses are very basic and incomplete examples. Estimates were made on Head loss through the hose. Estimates were made on NPSH Required.  Terrain, elevation, and temperature were not considered. MANURE WAS NOT CONSIDERED.

Efficiencies of the Engine matched to run the pump was not considered.  These examples do not show how PCE puts pump/engine units together nor how PCE would utilize these pumps.

If you'd like to go back through and see all these pumps at 1000 GPM, just use 38 ft. of Head Loss per 660 ft. of 6" hose.  The distances improve. 

Thanks,

Nancy

Inject the Nutrients

In second grade, we had to go around the room for the first time and tell everyone what our parents "do" for a living. August of 1992, I was almost 8. "My name is Nancy. My Dad bales hay and pumps. My mom helps farm." I took a seat.

"Nancy," My teacher interjected, "What does your dad 'pump'?"

"Manure," I answered quickly, starting to turn red in the face. She didn't have questions for anyone else. 

"Well, what does he do with it?" She asked, a bit uncomfortable.  

That's 2 questions. I glanced at one of the boys in my class - who's Dad was one of my Dad's customers; a bit uncertain if I needed to detail this or what she was asking. He wasn't any help.

"He spreads it on the field," I shrugged with a 'can't imagine what else he could do with it' innocence. 

I can still see the confused look on her face, and went through the rest of the day wondering what wasn't explained correctly. He pumps it, and spreads it on the field. What was so hard to understand?

Mom assured me that evening that I could just tell people they "farmed" and that was plenty to share. As they had been - mostly alfalfa, some corn, sheep, pigs, cows, chickens. But that year - we had 4 vacuum trucks parked in our yard, and 3 guys were working with Dad. It just seemed to me like they were pumping all the time, and if they weren't, they were making hay. It wasn't the same as the other kids in my class who's parents were farmers, and owned combines instead of windrowers and vacuum trucks, so I shrugged it off, and continued trying to explain to teachers what "pumping" was. 

Funny thing, it never ends. Although we are getting better at "explaining ourselves" to the non-agricultural community, some people are intrigued, some confused, some slightly disgusted. I guess it all depends on how well I "pitch" it that day.

This fall will be an exciting time. PCE has toys, and our customers have toys, and "big boys with big toys" are lots of fun to watch. 

Watching someone start a pump unit by clicking a computer mouse, just doesn't get old. Pulling out the yellow, hand-held, wireless remote and starting the agitation boat, standing on shore, and driving it around, isn't a bad way to work.   The best though, is when Jeremy skips the computer and uses his XOOM -- the touchscreen Android Tablet -- to start, throttle, and stop the pump units. Same goes for the Droid Phones.  Darn my iPhone, it doesn't allow Flash Player, required to run the MobileStar program.  I know pumping has it's "shit" moments, but for the first time since I was a kid, I'm looking forward to the ride-along seat in the new tractor this fall.

The dairy is calling, the choppers are running....