- last update 29.05.2004
TECHNICAL NOTES: technical considerations about relations between speed rotation and linearity of flow, correct criterions to select pumps for liquids and also for transfers of about solid products.
Following up many questions received by customers of ours we would like to propose you some technical considerations about the object.
Contrarily to what we heard sometimes to be affirmed by some customer, the correct rules to choice the most SOFT PUMP, depending on the application requested, remains to consider the revolutions rate number (of the pumping mechanical parts) requested to get the needed delivery capacity. In other words according to the needed capacity, the SLOWER pump WILL BE THE SOFTEST PUMP, even if the outgoing flow shouldnt be perfectly constant or linear.
We should think about, i.e., a centrifugal pump, like the ones we too produce, that have a perfectly constant output flow but working at 2800 revolutions per minute: the flow on pump exit will be perfectly linear and constant but we will have NO soft transfer because the mechanical parts WILL MOVE THE LIQUID about 70 TIMES MORE (for each minute of the transfer time) in comparison with a pump with mechanical parts working at 40 revolution rates per minute.
TO TRANSFER THE SAME PRODUCT QUANTITY THE MECHANICAL PARTS MOVING INSIDE THE PUMP WILL MOVE AND MIX THE LIQUID 70 TIMES MORE FOR EACH SINGLE MINUTE OF THE TRANSFER WORKING TIME.
So we should understand it is absolutely WRONG AND NOT CORRECT to associate the outgoing flow linearity and constancy with the concept of soft transfer: the slowest pump will be ALWAYS the most soft type of pump in comparison with the all the other TURNING AT HIGHER NUMBER OF REVOLUTIONS.
Therefore our technical advice about high quality wine would be to SUGGEST TO APPLY a PISTON PUMP or a PERISTALTIC PUMP both to be used, when possible, in first speed (35/40 revolution rates/min.) with a maximum delivery capacity from capacity from 12 up to 650 hl./hour at the lowest number of revolution possible on the market and in the second speed when necessary.
IMPORTANT: in case of emptying of BARRIQUES to avoid that the strong self priming power of the pistons pumps shakes the dregs deposits on the bottom of the barrel it is possible to reduce the self priming power and the transfer capacity (also up to zero), partially regulating the spherical inversion device (MANZINI patented) on purpose studied for BARRIQUES and for feeding heat exchangers.
On request it could be possible to propose an electronic inverter application to further slow down the revolution rates number.
In this case the less recommended type of pump would be the single screw pump because of the rubbing of the rotor on the stator, consequent risk of scorch (burning) of the same one and above all the revolution rates number (from 80 to 500-600) is clearly superior in comparison with a peristaltic or a piston pumps.
Rather than a single screw pump we suggest a stainless steel lobular pump nevertheless it curries out the same revolution rates number, or really similar, than a single screw pump but the lobular pump had no rubbing and friction on rubber parts in comparison with a single screw pump. This pump will curry out, like single crew pump, a revolution rates number (from 200 to 900 revolution rates/min. or from 80 to 400 for the low revolution rates/min model) ever clearly superior than a peristaltic or a piston pumps in the first speed or with electronic inverter (ONLY 35-40 turns per minute of the piston or of the peristaltic rotor in first speed and 70-80 in second speed).
For pressed de-stalked grapes transfers, in addiction, the peristaltic pump produce a VERY LOWER QUANTITY OF LEES (or DREGS) and TANNIN than a single screw pump. The single screw pump cause, in fact, the crushing of at least 30-50% of peels (GRAPE SKINS) cause the hard rubbing between the rotor and rubber stator, the peristaltic pump cause a clearly inferior crushing, about 15-20%, because the rolls, before to press the hose have the tendency to move the product behind and in front of the same roll.
The pump that cause the LOWER POSSIBLE LEVEL OF LEES AND TANNIN production is the piston pump because the only peels crushing point is caused by back movement of valves to their seats (in this point the crushing is however very lower, as regards surface and power, in comparison with a rotor of a single screw pump that must have an hydraulic seal against its rubber stator or with the rolls that compress the peristaltic pump hose till the complete closing of the same hose in order to have, also in this case, the hydraulic seal).
The piston instead, thanks to the FINISH RUNNING SECURITY SPACE that exist on each SUPERBA PISTON PUMP model (except for the KOMPREX model we supply only on request), never cross the suction and delivery passages (lights), so theres no cutting on peels (fruit skins) or pulps etc., in addiction always thanks to this space there is no crushing action on the fruits because the piston stop his movement about 30-50 mm (depending on the model) before the cylinder cover so it leaves a NO COMPRESSED space to avoid crushing and pressing dangerous for the quality of the transferred product.
This space consent also to avoid that eventually solid bodies could accidentally enter and damage the pump or the gear and/or reducer gear box.
So we would like to confirm that some of our piston pump models, as indicated on the our catalogue, work very well after FRUIT, VEGETABLE and GRAPE CRUSHERS, to transfer de-stalked grapes with a very gentle handling of the pulp and skins.
Infact, as from above, the number of revolution of the piston are very low and furthermore the piston never cut or press the skins because of the safety space at the end of the piston stroke.
MANZINI PUMPS - ITALY
THE TECHNICAL DIRECTION
- last update 29.05.2004
TECHNICAL NOTE: technical suggests in order to choice the correct type of pumps
1. The suggested pumps for dregs and skins of pressed grapes or fruits, whole grapes or fruits and semisolid products are as follows:
A. Peristaltic electric pumps model PE with or without hopper according to the type of employ. The main characteristics are: low number of revolutions rate, good transfer capacity, high pressure, up to 6 atm., high self-priming power, no damage with dry-functioning, medium/low crushing of the product, high cost, very low wear and spares needs.
B. Single screw pumps in the models MG 100, MT 100, MTT etc. The main characteristics are: medium/high number of revolutions rate, high transfer capacity, high pressure up to 6/12 atm., self-priming, NO dry-functioning, high crushing of the product, medium cost, medium wear and spares needs.
C. pumps with elliptic revolving piston model U.I. with hopper. The main characteristics are: low number of revolutions rate, low pressure up to 1/1.5 atm., NO self-priming, NO dry functioning, medium/low crushing of the product, low cost, very low wear and spares needs.
2. The suggested pumps for de-stalked and pressed grapes or fruits, fruits puree, etc. according to the lower revolutions rate number and the lower lees (dregs) and tannins production, in comparison with the other kind of pumps, owing to the absence of cut action and/or to the absence of crushing action on the transferred product (on the skins, grape/fruit inside stone, fruit/grape seeds, etc.) in addition to generic liquid transfers are as follows:
A. Piston pumps (only the models marked with P on the catalogue and particularly between the STANDARD SM240-SM320-2C520-620-720-820-920, and INOX SM 300-2C520-620-720-820-920-1000 1200). Characteristics: high delivery capacity, medium pressure up to 4,5 atm. in 1st. speed, 3.5 atm. in 2nd. speed, very high self-priming power, no damage for dry-working, very low or absolutely no crushing of the product, medium cost, very low wear and spares needs.
B. Peristaltic electric pumps model PE with or without hopper depending on the use. Characteristics: low number of revolutions rate, good delivery capacity, high pressure, till 10 atm., high self-priming, no damage with dry-functioning, crushing medium product, high cost, very low wear and spares needs.
3. The suggested pumps for filtration and bottling but not for simple transfers, as the revolutions rate number is higher, in comparison with the other pump models, are as follows:
A. Single screw pumps in the models MF, MG, etc. Characteristics: medium/high number of revolutions rate, high delivery capacity, high pressure, till 6/12 atm., good self-priming, NO dry-functioning, medium/high crushing of the product, medium cost, medium wear and spares needs.
B. Stainless steel lobe pumps models LI. Characteristics: medium/high number of revolutions rate, high pressure till 13 atm., NO self-priming, NO dry functioning, no mechanics parts rubbing on rubber parts, high cost, very low wear and spares needs.
MANZINI PUMPS - ITALY
THE TECHNICAL DIRECTION