Discussion about trouble shooting of mechanical sealing in submersible well pumps

Mechanical seal is also called end face seal. With the force from spring and sealing medium, it adds an appropriate amount of pressure on the contact surface between the rotating dynamic ring and the static ring the make their end faces touch each other closely.

A very thin layer of oil film is kept between the end faces. The medium will confront large resistance force when it passes through, which prevent leakage of fluids, achieving the effects of sealing. Meanwhile, this thin film also lubricates the dynamic ring and static ring.

If adjusted well, leakage can be prevented completely.

1. Features of submersible well pumps’ mechanical seal

The main advantage of the mechanical seal of submersible well pumps is reliable sealing. It rarely leaks in a very long period of operation. Its service life is long, generally 5 years on average, which also suggests a long maintenance period.

But mechanical seal has complex structure. It is manufactured and installed with high precision. It needs the maintenance personnel to be highly skillful. As the mechanical seal on oil delivery pipe is built-in type, we often need to dismantle the oil pump when maintaining the mechanical seal, which takes a large amount of work.

Therefore, it is of great importance to ensure reliable operation of the mechanical seal, and prolong the service life of mechanical seal.

2. Common problems of mechanical seal of the submersible well pumps

During operation, the main possible problems of mechanical seal are excessive amount of leakage and excess temperature.

Touch the gland of the mechanical seal with hand. If you cannot keep your hand on it for a moment, it indicates excess temperature.

The amount of leakage should not be more than 60 drops per minute. If the drops are in a line, it signifies excessive amount of leakage. If the seal ejects oil outward, you should stop the submersible well pumps at once for inspection.

For more information, please contact info@welpump.com 

Check out the problems of deep water well pumps by observation

We can find out if the parts on the deep water well pumps are loose, if there is any crack on it, and if it is injured, etc. though observation. We can find out if the lubrication is normal, if there is dry friction, if it leaks air or oil, etc. We can judge the wearing conditions of relative accessories by observing the amount, size and features of metal granules in the deposit at the oil box. We can monitor the deep water well pumps to see if it runs normally, if any abnormal phenomenon happens. We can watch the various meters installed on the equipment reflecting the working conditions of the deep water well pumps to know about the change of data. We can check the product quality and make a judgment about the working conditions of the equipment through measurement tools or by directly observing its surface.

By making a comprehensive analysis on every piece of information, we can judge whether the well pumps have any problem, where are the problems, how serious they are and their causes.

Through instrument, we can observe the worn particles collected from the lubricating oil of the equipment. An easy way of monitoring the wearing conditions of the pump is magnetic plug method.

The principle of this method is to insert a magnetic plug into the lubricating oil to collect iron particles as a result of wearing. By observing their size, amount and shape features through a reading microscope or with naked eyes directly, we can judge the wearing conditions on the surface of the mechanical parts.

By the way of magnetic plug, we can detect large particles caused by wearing of the machinery parts in later period.

If you see a small amount of tiny worn particles during observation, it means the equipment is running normally. If you see large particles, you should begin to pay much attention to the operation conditions of the pump. If you see large particles many times successively, it is a sign of failure in near future. At this time, you should stop the deep water well pumps at once, find out the problem and solve it.

The above explanation is detailed enough. It needs a long term of accumulated experience to judge exactly using these detection methods.

Find out the problems of 3 inch deep well submersible pump by hearing

Some primary simple methods usually used in monitoring the conditions of 3 inch deep well submersible pump are listening, touching and observing.

In this article, we will introduce the listening method only. The rest two methods will be introduced later. When the equipment is running normally, it will send out a rhythmic sound.  As long as you have become familiar with and mastered these normal rhythms and beats, you can compare it with the abnormal noise that is heavier, mussy or weird by listening to the pump, and find out the hidden dangers inside it, for example if anywhere is loose, clicking or unbalanced. Beat the accessories with a hammer and listen for a cracking sound to judge if it has any cracks. Electronic echo meter is a kind of vibration acceleration sensor. It changes the vibration conditions of the equipment to electrical signal and magnifies the signal. The workers wear an earphone to monitor the vibration sounds of the running equipment so as to realize observation measurement of the sounds. We can judge if there is anything wrong with the 3 inch deep well submersible pump by measuring the signals of one point, in different period, at same rotation speed and working conditions and comparing them. When you hear a clear and sharp noise from the earphone, it indicates higher frequency of vibration. This is generally because smaller and stronger accessories have local defects or tiny cracks. When you hear a turbid and deep noise from your earphone, it indicates lower vibration frequency. This is generally because larger and less strong accessories have big cracks or defects. If the noise you hear from your earphone is stronger than usual, it indicates the problem is worsening. Louder noise indicates more severe problems. If the noise you hear is mussy, intermittent and has no rhythm, it indicates some accessories or parts are loose.

Why does 3 inch diameter submersible deep well pump rotate so slowly?

Analysis on the causes for 3 inch diameter submersible deep well pump not sending out water

Air exists in the inlet pipe and the pump body

1) The self-priming deep well pump is not filled with enough water before it starts. Sometimes it may seems like the pump is full enough with water as you see water spilling out from the air discharge hole. But you didn’t turn the pump shaft to exhaust all the air, leaving a small amount of air remaining in the inlet pipe or pump body. 
2) The horizontal section of the inlet pipe connecting with the pump should run downward on a 0.5% slope in the direction contrary to the flow of water. The inlet of the pipe connecting with the deep well pump should be at the highest point, not completely horizontal. If the inlet pipe cocks, there will be air remaining in it, which will bring down the vacuum degree in water pipe and deep well pump, impacting suction. 
3) The packing of single stage 3 inch diameter submersible deep well pump is worn out as a result of long term operation, or is too loose, leading to a large amount of water ejected out from the clearance between the packing and the pump shaft sheath. That will allow air to enter the pump through this clearance, impacting the lifting of water. 
4) As the inlet pipe is always submerged under water, its wall will be corroded and hole. After the 3 inch diameter submersible deep well pump has started working, the water surface will keep dropping. When the holes are above water surface, air will enter the inlet pipe through them. 
5) The bends of inlet pipe crack. Even tiny clearance at the connection between inlet pipe and water pump will be possible for air to enter the inlet pipe.

The 3 inch diameter pump rotates at low speed

1) Human causes Some clients will drive the pump with another motor when the original motor breaks down. That will cause such consequences as small flow quantity, low head and even failure of lifting water. 
2) Mechanical failures of the submersible pump itself The fasten screws on impellers and pump shaft become loose or the pump shaft is distorted and bent, causing displacement of the impellers or damage to shaft bearing. As a result, the impellers will rub against the pump body directly. All these are possible causes for the decrease of the rotation speed of the pump. 
3) The motor is not well repaired. The motor is demagnetized because its windings are born out. If the number of coils of windings, the diameter of the wire or the way of wire connection is changed during maintenance, or the problems are not totally solved, the rotation speed of the water pump will also change.

Analysis on centrifugal pump leakage

What should we do if our centrifugal pump leaks

1. Leakage during installation and static test 

If the leak is not serious, it is most probably caused by seal ring problems of dynamic ring or static ring, while serious leaks indicate problems between the friction pairs of the two rings. After primary observation on the amount of leakage and judgment on the point of leakage, you can turn the pump with hand and observe the change of leakage amount. If the leakage doesn’t change obviously, then the problem must be in static and dynamic ring, friction pairs and the seal ring of the dynamic ring. Maybe the seal ring of static ring has become ineffective. Besides, it is also possible for the existence of leakage channels.

2. Leakage during test run

After static test on the mechanical seal of a centrifugal pump, the centrifugal force generated when the pump runs at high speed will hinder the leakage of fluid. Therefore, despite of ineffective seal in shaft and end cap, most leakage are caused by the damages to the friction pairs of dynamic ring and static ring. In most cases, you need to dismantle the friction pairs, change for a new one and reassemble it. 

3. Sudden leakage in normal operation 

If a centrifugal pump leaks suddenly during operation, it is most probably caused by tremendous change of working conditions or inappropriate operation or maintenance.  If the pump is exhausted, or holds pressure for rather a long time, or suffers from cavitation, the seal will be broken. If the practical output of the pump decreases, it will leave a large amount of fluids circulating inside the pump with heat accumulated simultaneously. That will vaporize the fluids and lead the seal to lose efficiency. If the pump has been idle for a long time, and you didn’t turn it with hand before starting it, the friction pair will be adhesive and tear the the surface of seal. If the medium begins to contain more corrosive, polymerism and gummy materials, or the environmental temperature changes sharply, the seal will also break. 

Faced with all the above kinds of leakage, we should find out a solution respectively, either change the seal or repair it. We should not mend it casually so as to make the centrifugal pump barely work for a longer time, and overhaul it until a more serious problem occurs.

Leak again?

Still leaking?

Come on,

Change for a shield pump, a magnetic pump for good.

Nine steps to select a sewage lift pump

We may often wonder how do people deal with and drain wastewater, such as rain water, dirty water generated in construction site and water having been used in bathing? WEL Pump Industry tells you that the treatment and drainage of sewage water needs a professional equipment, i.e. Sewage lift pump.

How could we find out which sewage lift pump is better, and how should choose from the brands of sewage lift pumps?

Now the WEL Pump industry will show you how to judge the quality of sewage lift pumps though nine of its performances.

Number 1, flow quantity

This refers to the amount of water discharged by a sewage lift pump in an hour. You can choose according to your own practical conditions.

Number 2, pump head

This refers to the maximum height the pump can lift the sewage water to. If you live on the first floor, you house may be 3m to 5m high. Considering about pipe loss, you need only 5m~8m head. But you should also make sure the flow quantity is enough too. Therefore, when selecting an integrated sewage lift pump, you should note the changing curve of flow quantity and head.

Number 3, diameter of flow-passing part

This indicates the maximum diameter of particles that can pass through the discharge pipes.

Number 4, protection level

The protection level for some parts of small sewage lift pump is IP44. Higher level stands for safer pump.

Number 5, case material

The case for sewage lift pump is generally PP/PE/ABS.

Number 6, heat dissipation

When the sewage lift pump is running, especially at high speed, its temperature will also be very high. In this case, heat dissipation will become an important index for measuring its performance.

Number 7, start control

That is to say under what condition is the sewage lift pump started, how is it controlled.

Small sewage pumps had better be pneumatic. Pneumatically controlled sewage pump will not get its floating ball winded and will not fail to start up. This is a fairly exact way of control.

Number 8, service life

Of course longer service life is better, since it can avoid the troubles of changing and maintaining. In order to save money, some clients will buy a cheap sewage pump produced in a small scale factory. At last, a few years later, the cost for maintenance and changing will surpass the cost for purchasing a more stable and safer sewage pump.

Number 9, the difficulty level in maintenance

Sewage pumps would go wrong. It will be a difficult task to dismantle and maintain the pump. The internal surface of the pump case will be dirty after some time of operation.

How to select 12 hp deep well submersible pumps?

12 hp deep well submersible pumps are a kind of vertical multistage centrifugal pump. It gets water out of deep wells.

With the underground water level dropping, deep well pumps are more widely used than common centrifugal pumps.

However, some clients didn’t choose a correct model of pump. As a result, either the pump doesn’t fit in with the well, or it can not send out water or send out enough water. Even the well may be damaged.

So how should a client select a deep well pump correctly?

1. We should choose submersible multistage pump according to the allowed maximum yield of the well of water source.

The practical flow quantity must be in line with the actual yield of the water well. It must be equal to or a little smaller than the actual yield. Otherwise, forced pumping will be inevitable, which will not only shorten the service life of the deep well submersible pump, but also, in worse condition, damage the filter screen, causing unstoppable flowing of sands, or even ruin the water well.

2. The diameter of 12 hp deep well submersible pumps must be in line with the diameter of the well.

To make it easy to hoist up and put down the deep well pump, to make the underground water accumulate quickly if any space is available with no resistance, and to reduce of the pump in operation, the well diameter from lifting pipe to pump body should be larger than the maximum diameter of the pump by 20~40mm. That is, the part of the pump with the largest diameter should have a 10~20mm annular clearance to the wall of the well. In this way, the service life of both the well and the deep well pump can be prolonged.

3. When you put the pump down into the well, never put the pump head at the position of the filter pipe, but at the position of the well wall pipe. Otherwise, when the pump works, it will cause unstoppable flowing of sands or damage the well.

We should decide the shaft forming structure of the well (well diameter, pipes positions), the depth of the well and the model of water pump according to the well logging curves of the manhole and the hydro-geological conditions of the well in question and adjacent water wells (including the depth, thickness and litho logy of the water source) and the operation conditions of the water pump, so as to avoid any possible problems in future when putting down the 12 hp deep well submersible pumps or the pump is running.

Contact: info@welpump.com