Reasons to use them

Why should I use a hose carrier instead of a pump of other type?

There are different type of volumetric pumps , each has different properties from other , for example some pumps guarantee higher pressures at equal power, other flow rates. There are types of pumps that are more suitable for treating solid bodies of significant size, other more indicated for aggressive fluids and so forth.

There is no machine “perfect” in absolute, however you can choose the one that will give you less problems. Often, in plants can be seen applied surprisingly pumps totally unsuitable or anyway not appropriate.

This “phenomenon”, often happens when we emulate an application that has already been carried out by others, sometime, the designers do not venture out by abitudinari contexts. They replicates with continuity the same solution, the same system or the same pump because it ihas always done so. Sometimes designers uses the best known brand, so to avoid doubts and criticisms.

Often the customer or end user, hear from designer, “what do you want?, I chose the best on the market, what can I do more than that”.

Yes it is possible definitely, but it is not easy, you would have to know all the pumps for typology, have merits and defects, is complicated, especially if the pump is not that one of the many components of a system. Then we goes on with what is known with the always habits, replicating at infinity also choices without sense. Any problems are simply left to the end user, which if he wishes, will deviate from the usual solutions at his own risk and peril. Perhaps there is no risk, probably neither danger, but in a wrong choice, there are certainly safe malfunctions and onerous costs.

We have seen applications with  progressive cavity pumps (which are irreplaceable for some purposes) installed in such a way senseless, only because this pumps are more wide spread and mostly known, and it is true. It is also true that frequent and incorrect use generates very high costs that are normal and physiological considered , as if there were no other possible choice..

Nothing more wrong, sometimes the choice of type of pump toward a more suitable is only dictated by custom or habits, not by careful project analysis.

What can we do so? In the meantime let us ask a few is simple basic questions, because it is this that saves, we come to the point and let us ask ourselves:

  1. The fluid I have to pump is below the level of the suction mouth of the pump?
  2. The fluid I have to pump is above the level of the suction mouth of the pump?

If the fluid is located below the pump, (condition 1) it must be considered that the pump should be self priming type and capable to asprate the liquid inside it, and therefore might have more or less long periods of intermittent operation or even dry. It will be good to avoid using pumps not able to ensure the dry operation as the pumps progressive cavity (single-screw), gears, some lobe pumps because it would destroy rapidly. Some companies sell for the  purpose protection devices against dry running for the abovementioned pumps, more useful (to those who sells them). If you think to trust these devices in the presence of “difficult” fluids , we can do no other than to wish you good luck. Better things is get informations, analyze the various types of pumps.

Such pumps may also operate dry without damage?

Classic diaphragm pumps , electric or pneumatic do not pose a problem in the case of dry operation, there are a limits of suction if the pump strat with dry valves, you can not expect more than 4 meters of vacuum. The situation changes working on wet valves, in this case you can get up to 7 – 8 meters of vacuum.

The  tubular membrane Hose carrier pumps (peristaltic pumps), can operate stably even when dry and can always guarantee a vacuum capabilities of 8-9.5 meters according to models.

Some lobe pumps are able to prime and also operate dry without damage to the pump, but to avoid problems, first must clarify this possibility with the manufacturer.

All other pumps, may not run dry.

If the fluid is located above the pump, (condition 2) it is not difficult to make mistakes, in this case every pump work perfetcly, because 50% of fatigue makes the gravity itself, and the pump remain flooded, the machine will only “transfer” the fluid. The consequent selection phase on the pump choice provides these questions:

  1. Is the fluid chemically aggressive?
  2. Is the fluid mechanically abrasive?

Fluidi chimici aggressivi. 

In the presence of particularly aggressive fluids,  pumps that can offer the most compatibility are certainly diaphragm pneumatic pumps because they are made of various materials, metallic and synthetic, may use membranes coupled with PTFE , as is known, this material has a very high resistance to the aggression. The performance will be however limited by the fact that the PTFE, is not an elastomer and has a minimum strength, therefore, to ensure the durability of the membrane, the flow rate of the pumps must be reduced up to 50%. The cost to pay for this excellent chemical compatibility (besides the exorbitant of compressed air cost required), hides in the materials themselves, pumps constructed in stainless steels special or PTFE are very, very expensive.

The Hose Carrier pumps  offers a wide compatibility, 95 % of the substances may be pumped at low costs for a simple reason. The pumped fluid, remains contained within the tubular membrane and is in contact only with the attacks and the membrane itself. If there is compatibility between the fluid to be pumped and the tubular membrane, perfect economically combination in obtained. It is unnecessary that the pump needs to be built with different materials from the standard, unless for other reasons. This is unique feature in the Hose Carrier pumps , so lowers costs are  really significant. There is in any case the possibility of realising the Pump Hose Carrier in various materials if necessary. The tubular membranes, are available in different materials in order to ensure maximum chemical compatibility.

The  progressive cavity pumps and some lobes have a limited resistance due to materials with which may be produced. This pumps are available in cast iron and stainless steel, resistant since we want, but it will not be possible to have a wide compatibility. You can rightly argue that there are also the surface coatings such as chrome plating, ceramics, and other various treatments, ennoble and elevate the quality of the product, but also the costs,  a few deep scratches to generate rapid destructive phenomena. For direct experience and verified in dozens of cases it is best to try the full compatibility between the pump and the product to be pumped without shortcuts.

The erosive fluids and solid abrasive suspensions. 

Nothing lasts forever, sooner or later all pumps suffer the effects of wear. Recognized that it is not possible to obtain the ideal duration, it is necessary to accept the hypothesis to provide maintenance costs to assess whether it is or less in the criteria of acceptability. Let us see what parts are subjected to wear in various pumps, restricting ourselves to those provided for the normal recovery suggested by the manufacturer.

Progressive cavity pumps (monoscrew): stator and rotor, hydraulic seal, transmission coupling inside. (at least 4 components).

Lobe pumps: the lobes, monolithic or composites, the pump body, the protective shields (any), Mechanical Seals. (at least from 4 to 8 parts).

Diaphragm Pumps: membrane, the valves, valve seats (5 components for any single pump body).

Hose Carrier Pumps with a tubular membrane  (peristaltic pump): the tubular membrane (1 component).

The answer to every economic doubt  resolves in a simple arithmetic operation, by calculating the cost of the components necessary for the recovery of the pumps.

But how does the wear affects the various type of pumps taken into consideration?

Diaphragm Pumps

Diaphragm pumps are probably the best from this point of view, the duration of the membrane and valve system is certainly very good, the pump body does not suffer for significant damage. The cost of the parts is quite modest thanks to the great diffusion of these pumps in all industrial sectors. The replacement of the parts is relatively simple but provides for the great majority of models the removal of piping to allow disassembly of the pump necessary for replacement of parts. The real weak point of diaphragm pumps pneumatic consists in the need of a high quantity of compressed air destined to mechanical ower supply, if you must work with significant flow rates, it is necessary one compressor for any pump. The cost of the compressor, the pneumatic line and the related energy burden and maintenance are constantly reducing the operational advantage of these pumps that have been for decades  the most widely used in each sector. If the pumps must e to be used as dosing pumps, devices and apparatus are required to prevent the “stall” of the compressed air and  is not easy thing to realize, also the environment temperature is important for these pumps, winter Calibrations will not work well during the summer climate

Pompe a cavità progressiva (monovite)

Although it is true that these pumps can ensure high levels of pressure even when operating with abrasive fluids, it is equally true that maintenace costs are very high. The purchase price in relation to other pumps is safe convenience, progressive cavity pumps are very compact and suitable to be inserted in the plant. But at the purchase price will follow in short time the enormous cost of parts, which are not always properly estimated, or completely ignored because thats is the responsibility of the end user. As often happens especially between designers and builders of plants, whose purpose is sell not use this pumps. The progressive cavity pump works really good with many products even very high viscosity, but cannot pump solid sharp bodies  this strictly effects wear of components. Elastomeric stator and rotor in  metallic material, are in constant friction. These two components must be replaced, perhaps at different times, but it is not said that are a long time, depends on the nature of the fluid. Even if the cost of the parts may be relative acceptable (and this is not always true), the frequency of their replacement raises the costs of management in a very significant way. You must add occasionally also the cost of the sealing system and the joints (where envisaged) because they remain always in contact with the pumped fluid. Repair requires disassembly almost whole the pump and the piping, it is often necessary to remove the pump and bring it in a workshop equipped to repair, especially for the larger models where the force required to remove and replace the components are anything but irrelevant (let us think for a seized rotor in the stator). The specialized manpower and transfers cost, by adding the cost of spare parts, show up costs that quickly clarify the reasons you need to understand that it is better to apply the  progressive cavity pumps in “sensible” way or try an alternative. These pumps are those that we often replace with our Hose Carrier, precisely for the reasons indicated above.

Lobes pump

The substance does not change, the wear on these pumps acts very quickly and this explains why some versions are equipped with shields and the protection plates replaceable and rotors with lobes individually replaceable. Restore operations of the pump shall be carried out in a rather fast and practical, and if you do not arrive at a deep wear of the machine, it is possible to restore spares without having to remove the pipes. The cost of the parts is very consistent and are particularly vulnerable to the compact solids of high proportion, that tear down or damage the lobes and “scratch” the shields. The presence of two rotating shafts inside the pump body does not help for certain in the presence of long fibers. Their unique characteristic consists in the great compactness and combined to bring relevant flow rates, unattainable for all other types of volumetric pumps, characteristics that can be obtained thanks to the high number of revolutions turns. But  precisely in this consists the vulnerability of this pumps, high speed becomes inevitably rapid wear, even the pumping of solid sharp bodies , especially those pumps with rubber lobes inside  .

Pompe a membrana tubolare Hose Carrier (peristaltiche).

In the Hose Carrier peristaltic pumps,  wear is an issue that involves only the tubular membrane. This is the only component in contact with the erosive fluid, we can say that hose constitutes practically the pump body itself. The tubular membrane is made of different materials, with or without textile fiber reinforcements in  according to the pressure that the pump must guarantee, the wear resistance to the mechanical action is rather high, comparable to that of traditional diaphragm pumps . Are very durable because there is no friction. The rotation speed is very low when compared to lobe pumps or progressive cavity pumps. The cost of the tubular membrane part is comparable to the stator of a progressive cavity pump. The great advantage of the Hose Carrier Pumps  consists precisely in the presence of a single wear component, which has cost truly economically sustainable, without any increase in costs hidden. The replacement of the tubular membrane never requires disassembly of the pump or the pipes, it is achivable very rapidly without particular expertise, directly on site and by personnel with normal skills. It is appropriate to clarify that in the application of the Hose Carrier Pumps  there are limitations, this are not ideal for pumping solid sharp bodies. Hose carrer pumps are very low speed kind of pumps , therefore, if this pumps are very resistant to abrasion and wear, are also more voluminous in relation to other pumps, engaging more space.

In substance

Habits and customs are a nice thing, as well as break down some hidden costs and improve the functionality of a plant or an application. Spend a few phone calls or gather some more information could even eliminate hassles in the future. We believe it is worth the effort.