centrifugal pump 75 mm

When they say “centrifugal pump 75 mm?”, many people immediately think about the pipe. And this is the first mistake. In selection practice, especially for chemical media or water supply systems, 75 mm is most often a conditional passage at the inlet/outlet, but not a defining characteristic. The key factors are pressure, flow, material of the flow part and type of seal. At our Zhejiang Yangzijiang Pumping Industry Co., Ltd., we constantly see on test benches how customers come with the request “need a 75th pump?”, and leave with a completely different model after analyzing the actual conditions.

Why ?75 mm? may be misleading

Take, for example, our linecentrifugal pumps. There are models with a 75 mm connection, but single-stage for clean water and multi-stage for increasing pressure are technically different devices. The diameter is the same, but the impellers, shafts, chambers are different. A common problem at sites: the customer installs a pump according to the diameter of the pipeline, and then wonders why it does not hold the required pressure or overheats. The issue here is not the diameter, but the curve of the pump, which did not coincide with the characteristics of the system.

There was an incident at one of the chemical plants near St. Petersburg. Requestedcentrifugal pump 75 mmfor pumping alkaline solution. The diameter was suitable for our standard cast iron model. But after requesting data on temperature and concentration, it became clear that a full-fledgedchemical pumpmade of stainless steel AISI 304 with mechanical seal made of silicon carbide. If they had shipped it on the first request, they would have suffered corrosion and leakage within a month. Therefore, our company has a whole procedure for clarifying parameters: environment, temperature, presence of abrasive, operating mode. Without this, even starting a conversation is pointless.

Or here’s another point: 75 mm is DN80 according to the standard. But flanges can be for different pressures, from PN6 to PN16. In a hurry, installers sometimes don’t look, they connect just about anything, and then they are surprised by leaks at the joints. This is no longer the fault of the pump, but the overall selection picture becomes lopsided.

Production experience: from drawing to testing

Our eight production lines at Zhejiang Yangzijiang Pumping Industry Co., Ltd. process the samecentrifugal pumpat 75 mm it starts not from the workshop, but from the development department. Engineers look not at catalogs, but at test data from similar models. For example, for self-priming pumps with such a connection, the shape of the volute and the clearance of the impeller are critical - the slightest deviation, and the efficiency drops by 5-7%, and cavitation begins earlier.

I personally saw how, at the testing stage, a pump that was ideal for water “choked.” on a viscous liquid. I had to recalculate the angle of the blades and increase the engine power. There is no ready-made formula - there is experience and bench runs. Therefore on the siteyangtzeriverpump.ruWe always indicate: the parameters are given for water at 20°C. For other environments, please contact the technical department.

It is especially difficult with 75 mm magnetic pumps. Here, in addition to hydraulics, it is necessary to accurately calculate the magnetic coupling so that the moment of transmission of torque is with a reserve, but without overheating. Once there was a complaint - the pump stopped when the density of the liquid increased. We figured it out - the torque reserve was calculated theoretically, without taking into account possible viscosity fluctuations. Now for such orders we do additional tests on glycerin mixtures.

Typical application scenarios and installation errors

Most often, pumps with a 75 mm connection are ordered from us for two things: pumping water in irrigation systems and as unloading pumps for containers with chemicals. In the first case, the main enemy is sand and suspended matter. Even if the pump is cast iron, the abrasive “eats up” in a couple of seasons. impeller and sealing rings. We recommend installing a filter, but many people skimp. Then they wonder why the supply dropped.

In the second scenario, with chemistry, the main problem is the incompatibility of the material. Our PP or PVDF plastic chemical pumps are good for acids, but there are some caveats. For example, PVDF is not suitable for some organic solvents; 316L stainless steel is needed. And its cost is already many times higher. Clients sometimes try to save money, take what is cheaper, and then change the entire device after the first pumping. It’s more profitable to choose the right one once.

More from practice: installation. It would seem that I screwed the flanges and connected the power. But if there is a straight pipe at the suction less than 5 diameters from the pump, or if there are sharp turns, turbulence occurs, the pump works with cavitation, makes noise and quickly fails. This is in the instructions, but they rarely read it.

Comparison with other types of pumps for similar tasks

Sometimes for tasks where they requestcentrifugal pump 75 mm, another type is better suited. Let's say you need to pump a thick suspension. The centrifugal one will constantly clog and require washing. Might work heresingle screw pump(screw) of the same connection. Its feed rate is not as high, but it copes well with viscous and heterogeneous media. We have a line of such pumps in our production, and they are often preferable for food production or pulp mills.

Or the situation with volatile liquids. Complete tightness is critical for them. A magnetic pump with a sealless seal is an ideal solution, although its efficiency will be slightly lower than that of a conventional centrifugal pump. But zero leakage.

Therefore, our approach at Zhejiang Yangzijiang Pump Industry Co.,Ltd is not to sell a specific model, but to offer a technical solution. Often, after a dialogue with an engineer, a customer with “needs a 75 mm centrifugal?” comes to ordering a diaphragm or submersible pump. And that's right.

What to look at beyond the catalogue: maintenance and durability

Any pump, even the highest quality, requires maintenance. For centrifugal ones with a mechanical seal, this is checking the wear of the sealing pairs and replacing the stuffing box (if any). On our models we try to make a dismountable case with a minimum set of tools so that replacement can be carried out on site, without sending it to the factory.

The resource greatly depends on the mode. If the pump operates 24/7 at nominal parameters, it can last 5-7 years before major repairs. If it constantly turns on/off or works “in a closed valve?” – the resource drops significantly. We also warn you about this.

And lastly: spare parts. On ouryangtzeriverpump.ruMain components are always available - impellers, shafts, seals for popular models. Because we know: stopping a pump in production means downtime and losses. Fast delivery of spare parts is part of our service policy.

As a result, returning to “centrifugal pump 75 mm”: this is not the name of the product, but one of the parameters in a long chain of choice. You need to start with the task, not with the diameter of the pipe. And it’s good when a manufacturer, like ours, can not only make a device, but also help you understand the nuances of its use, and, if necessary, offer an alternative. Then the equipment works for years, and there are minimal problems with it.