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Re-inventing the pump
Re-inventing
the pump
More than twenty years ago my father, Frank Wilkinson, who spent most of his working life as a re search C development centrelathe turner, needed to empty the soluble oil (iutting lubricant) sump of his lathe and couldn’t j8nd a suitably easy way of doing it. He dectded to make himself a simple pump to do thejob and in an afternoon thefirst version of a novel device was born. It was very simple, with or&$nally only two moving parts, but did the job admirably. Particularly useful in this instance was its suction bead and reversible flow. Next the pump was used for circulating the family fibpond andproviding a decorative aerating fountain.
continued to deliver and improved all the time. As I became more astute in my own business career, and recognised the commercial potential, I invited various companies to examine the technology. Ingersoll Dresser were particularly helpful with both materials and testing facilities (our thanks go to Mr John Dodson) as our own purpose built shed-come-workshop is quite basic (although my engineering/computing background came in useful for our own “HeathRobinson” tests). Progress was slow because I have a full-time career in another field, and corporate giants move slowly when they are doing well and even more slowly when they are busy inhouse fire fighting. Today the “Reciprotary” pump as it has been called has significant potential for the right-minded organisation wishing to exploit it and I summa&e it as follows:
Description
The Reciprotary pump originally had only two moving parts.
There it stayed for many years until I was old enough to recognise some real potential in the device (one of many my father produced) and to undergo both a practical and intellectual exercise by developing it further and applying for patent in 1987. We experimented with different materials from stainless steel and brass through epoxy to acetyl and various plastics. We tried various relative dimensions, timing arrangements and stroke volume etc., and the unit
Current embodiments of the pump comprise three moving parts with an in-line body housing a rotor with transverse bore containing single piston driven by an eccentric pin via a cross-slide or scotch yoke mechanism. That’s it basically, no valves, no complications and a performance which has been a surprise to many ardent pump technology engineers. With a prototype having a piston measuring approximately 1” (2.5 cm) in diameter and the whole unit being 6” (15 cm) round and the same in length (excluding motor) it produced in excess of 100 meter head of water with a fully open flow rate of 1 m3/hr. This represents the equivalent performance of a multi-stage centrifugal pump ten times that dimension! The real beauty remains its simplicity which obviously lends itself to cost-effective manufacture.
Positioning In later tests it was found that because of the design there are no special sealing requirements. In fact it could be made with a plain ceramic type bearing/seal combination without compromising performance. Original prototypes had a standard Crane seal and single ball bearing on the shaft with a set of slip rings as a bearing to support the rotor at the cover plate end. What this in
Copyright
Q
1996,
Elsevier Science Ltd. All rights reserved.
The Reciprotary pump’s niche lies between multistage centrifugal and low end PD types.
effect means is that the whole unit can be made very easily by a number of methods of which one is obviously injection or lost-wax moulding. It has been a marketing challenge to position Reciprotary as it is patently a positive displacement pump, and suffers some of their inherent drawbacks: it does not tolerate solids in suspension and has a steep HQ curve. A more attractive option is the replacement of centrifugal pumps in clean fluid applications. In reality it has a place between multi-stage centrifugal and low end PD types, overlapping both markets with its field of use restricted only by the HQ curve and requirement for filtration. I enclose the table below to assist in comparisons. The only unknown, due to lack of extensive testing, is the longevity and reliability of the Reciprotary design but from the technology incorporated it is estimated that hITBF figures would be as good if not better than any other PD pump. It is the authors’ firm belief that once established for specific applications such as heating and ventilation, paint spraying and Vortex Reciprocating/Rotary Valveless Close Clearances Level of Pulsation Complexity Fluid Lubricated Steep HQ Curve Reliability Manufacturing Cost
Rotary Yes No Low Low No No Good Low
general process, demand for Reciprotary to replace centrifugals in other generic areas will be led on price versus performance.
Performance Test data, courtesy of Ingersoll Dresser, is shown graphically overleaf. The unit in question was all metal construction.
Benefits Independent fluid engineering analysis coneludes that Reciprotary has the following advantages: Key l Compact l Efficient l I&w Cost Primary l High NPSH
Reciprotary Hybrid Yes Yes Low Low Yes Yes ? Low
Gear/Screw
Plunger/Piston
Rotary Yes Yes Low Low Yes Yes Good Medium
WORLD
Reciprocating No Yes High High No Yes Poor High
PUMPS
FEBRUARY
1996
l
l
l l l
l
l l
I
I
1.4
1.2
eciprotary performance.
Lower tolerance of solids in suspension than impeller Lower tolerance to “shut-off’ conditions than impeller Subject to greater wear than non-PD pumps Shorter lifespan than impeller Lower rotational speed upper limit than impeller Greater noise/vibration/pulsation than impeller Narrower range of scalability than impeller Narrower range of applications due to steep HQ curve than impeller
Conclusion
pump
Self Priming (No Sump) l No reverse leakage path when stationary l No non-return valves required Secondary l Can be all metal construction l Can be moulded and coated 0 Tn line construction Disadvantages identified were:- (note these are all compared with non-PD types) l More complex than impeller l
We Can Cartridge
Furnish
Any
For an application requiring a pump which delivers better head rating/performance than a centrifugal type (for clean fluid applications) at centrifugal pump prices, there is no other comparable pump. Reciprotary clearly demands some attention. There is room in the market for Reciprotary and it will be interesting to see how a classically conservative engineering industry accepts and accommodates a novel version of a device as familiar to them as the wheel. n
Type
of Seal
gland, Metal bellow, Teflon bellow, and Split’Seals
Duplicatesof Crane Types1, 2,6,6e, 8,9, 21 . Dura RO, RA, PTO. B-WStyles U, UZ on the shelf. ‘,I
,,a. f ,,i‘,
We Furnish all Metallurgy Any Face Combination . . . . . . . . . . ti Best Quality ti Fastest Delivery 4 Lowest Price . . . . . . . . . . . . .
We are looking for Dealers and Distributors in all countries. We duplicate
-SEAL
PEOPLE
. ~51)~~tZ~~~
VI& Welcome OEM Accounts
R.1 Seal Parts & Repair Co. s 1330 Sherwoob Forest, Houston TX 77043 USA Tel: (713) 461-6634 Fax: (713) 461-4742
Seal Repair Custom Build Sizes in Inches & Metric
WORLD
PUMPS
FEBRUARY
1996
the pump
More than twenty years ago my father, Frank Wilkinson, who spent most of his working life as a re search C development centrelathe turner, needed to empty the soluble oil (iutting lubricant) sump of his lathe and couldn’t j8nd a suitably easy way of doing it. He dectded to make himself a simple pump to do thejob and in an afternoon thefirst version of a novel device was born. It was very simple, with or&$nally only two moving parts, but did the job admirably. Particularly useful in this instance was its suction bead and reversible flow. Next the pump was used for circulating the family fibpond andproviding a decorative aerating fountain.
continued to deliver and improved all the time. As I became more astute in my own business career, and recognised the commercial potential, I invited various companies to examine the technology. Ingersoll Dresser were particularly helpful with both materials and testing facilities (our thanks go to Mr John Dodson) as our own purpose built shed-come-workshop is quite basic (although my engineering/computing background came in useful for our own “HeathRobinson” tests). Progress was slow because I have a full-time career in another field, and corporate giants move slowly when they are doing well and even more slowly when they are busy inhouse fire fighting. Today the “Reciprotary” pump as it has been called has significant potential for the right-minded organisation wishing to exploit it and I summa&e it as follows:
Description
The Reciprotary pump originally had only two moving parts.
There it stayed for many years until I was old enough to recognise some real potential in the device (one of many my father produced) and to undergo both a practical and intellectual exercise by developing it further and applying for patent in 1987. We experimented with different materials from stainless steel and brass through epoxy to acetyl and various plastics. We tried various relative dimensions, timing arrangements and stroke volume etc., and the unit
Current embodiments of the pump comprise three moving parts with an in-line body housing a rotor with transverse bore containing single piston driven by an eccentric pin via a cross-slide or scotch yoke mechanism. That’s it basically, no valves, no complications and a performance which has been a surprise to many ardent pump technology engineers. With a prototype having a piston measuring approximately 1” (2.5 cm) in diameter and the whole unit being 6” (15 cm) round and the same in length (excluding motor) it produced in excess of 100 meter head of water with a fully open flow rate of 1 m3/hr. This represents the equivalent performance of a multi-stage centrifugal pump ten times that dimension! The real beauty remains its simplicity which obviously lends itself to cost-effective manufacture.
Positioning In later tests it was found that because of the design there are no special sealing requirements. In fact it could be made with a plain ceramic type bearing/seal combination without compromising performance. Original prototypes had a standard Crane seal and single ball bearing on the shaft with a set of slip rings as a bearing to support the rotor at the cover plate end. What this in
Copyright
Q
1996,
Elsevier Science Ltd. All rights reserved.
The Reciprotary pump’s niche lies between multistage centrifugal and low end PD types.
effect means is that the whole unit can be made very easily by a number of methods of which one is obviously injection or lost-wax moulding. It has been a marketing challenge to position Reciprotary as it is patently a positive displacement pump, and suffers some of their inherent drawbacks: it does not tolerate solids in suspension and has a steep HQ curve. A more attractive option is the replacement of centrifugal pumps in clean fluid applications. In reality it has a place between multi-stage centrifugal and low end PD types, overlapping both markets with its field of use restricted only by the HQ curve and requirement for filtration. I enclose the table below to assist in comparisons. The only unknown, due to lack of extensive testing, is the longevity and reliability of the Reciprotary design but from the technology incorporated it is estimated that hITBF figures would be as good if not better than any other PD pump. It is the authors’ firm belief that once established for specific applications such as heating and ventilation, paint spraying and Vortex Reciprocating/Rotary Valveless Close Clearances Level of Pulsation Complexity Fluid Lubricated Steep HQ Curve Reliability Manufacturing Cost
Rotary Yes No Low Low No No Good Low
general process, demand for Reciprotary to replace centrifugals in other generic areas will be led on price versus performance.
Performance Test data, courtesy of Ingersoll Dresser, is shown graphically overleaf. The unit in question was all metal construction.
Benefits Independent fluid engineering analysis coneludes that Reciprotary has the following advantages: Key l Compact l Efficient l I&w Cost Primary l High NPSH
Reciprotary Hybrid Yes Yes Low Low Yes Yes ? Low
Gear/Screw
Plunger/Piston
Rotary Yes Yes Low Low Yes Yes Good Medium
WORLD
Reciprocating No Yes High High No Yes Poor High
PUMPS
FEBRUARY
1996
l
l
l l l
l
l l
I
I
1.4
1.2
eciprotary performance.
Lower tolerance of solids in suspension than impeller Lower tolerance to “shut-off’ conditions than impeller Subject to greater wear than non-PD pumps Shorter lifespan than impeller Lower rotational speed upper limit than impeller Greater noise/vibration/pulsation than impeller Narrower range of scalability than impeller Narrower range of applications due to steep HQ curve than impeller
Conclusion
pump
Self Priming (No Sump) l No reverse leakage path when stationary l No non-return valves required Secondary l Can be all metal construction l Can be moulded and coated 0 Tn line construction Disadvantages identified were:- (note these are all compared with non-PD types) l More complex than impeller l
We Can Cartridge
Furnish
Any
For an application requiring a pump which delivers better head rating/performance than a centrifugal type (for clean fluid applications) at centrifugal pump prices, there is no other comparable pump. Reciprotary clearly demands some attention. There is room in the market for Reciprotary and it will be interesting to see how a classically conservative engineering industry accepts and accommodates a novel version of a device as familiar to them as the wheel. n
Type
of Seal
gland, Metal bellow, Teflon bellow, and Split’Seals
Duplicatesof Crane Types1, 2,6,6e, 8,9, 21 . Dura RO, RA, PTO. B-WStyles U, UZ on the shelf. ‘,I
,,a. f ,,i‘,
We Furnish all Metallurgy Any Face Combination . . . . . . . . . . ti Best Quality ti Fastest Delivery 4 Lowest Price . . . . . . . . . . . . .
We are looking for Dealers and Distributors in all countries. We duplicate
-SEAL
PEOPLE
. ~51)~~tZ~~~
VI& Welcome OEM Accounts
R.1 Seal Parts & Repair Co. s 1330 Sherwoob Forest, Houston TX 77043 USA Tel: (713) 461-6634 Fax: (713) 461-4742
Seal Repair Custom Build Sizes in Inches & Metric
WORLD
PUMPS
FEBRUARY
1996