Causes and solutions to excessive pump noise
The noise of the pump may have the following reasons:
(1) The impact of the rotary vane on the cylinder body, the sound volume of the residual volume of the water pump and the pressure oil in the exhaust dead space;
(2) Impact of the exhaust valve plate on the valve seat and the support member;
(3) Echoes and bubble bursts in the cabinet;
(4) bearing noise;
(5) Noise caused by a large number of gas and oil impact shields;
(6) Others. Such as noise caused by the transmission, fan noise of air-cooled pumps, etc.
(7) Motor noise, which is a crucial factor.
Divide as follows:
1) Impact of the rotary plate on the cylinder wall. If the design, manufacture, or improper use of materials causes slides to slip, or due to the presence of exhaust dead gaps, the incompressible oil causes the rotor head to not always work against the cylinder wall, causing the rotor to be against the cylinder wall. Impact sound. Therefore, it is advisable to adopt a structure in which the arc is partitioned into the exhaust port. Use exhaust runners to eliminate dead space. When using a line-separation structure, the distance from the exhaust end point to the tangent point should be as short as possible. For a rotary-slide pump of 70L/s or less, consider the actual thickness of the rotary slat, it is recommended to take 7-lOmm, and the large water pump takes a large value. When it is too close, because there is only one narrow belt contact with the rotor head due to the presence of the rotor vane groove, once the rotary vane reaches the tangent point, the sealing effect will not affect the pumping speed or even the ultimate pressure. It can be seen that this structure cannot completely eliminate exhaust dead space and limits the level of noise reduction.
It should be pointed out that the gap between the rotor and the slot is too large to reduce the performance. Therefore, to ensure a reasonable tolerance and shape tolerance values, pay attention to the thermal expansion of the rotary vane, to avoid the rotation of the rotary vane and the groove, pay attention to the oil's cold oil viscosity, and design enough spring force of the rotary vane to use the garden arc surface separation. The additional eccentricity of the rotor center should not be too large. Otherwise, if the rotary vane passes through two arcs, it will tend to separate from the cylinder wall at the intersection point, which will cause impact noise. General small water pump can be 0.20 ~ 0.25mm, large pumps can be properly increased.
The pressure oil in the exhaust dead space and the pressure oil in the residual volume sounded. When the water pump reaches the limit pressure, the two pressure oils will shoot at a high speed to the vacuum chamber when they are connected to the vacuum chamber, and they will make a sound with the rotor and the cylinder wall. The size and position of the two volumes are related to noise.
2) Impact noise of valve seat on valve seat and support
The amount of gas sucked in is large, the amount of circulating oil of the pump is large, the noise of the valve piece is larger, the valve jumps high, the area of ​​the valve is large, the noise of the valve piece is also large, and the material of the valve plate also has a certain influence. Rubber sheet noise should be better than steel sheet or laminate. For this reason, it is necessary to control the amount of oil to be fed in. The closure of the valve plate must be prompt and strict. Pay attention to the selection and structure of the valve.
3) When the sound volume of the echo and air bubbles in the box increases, the noise will increase. Therefore, this noise will increase significantly when the town is opened or when the atmosphere is open. If the gas volume is adjustable, the amount of gas can be adjusted properly.
4) Noise emitted when a large amount of gas and oil are discharged and impact parts such as oil baffles. If the part is not rigid enough, or if it is not tightened, vibration and collision will occur, which will increase the noise. Therefore, the oil baffle plate should not only have sufficient rigidity and be fastened, but also, when it is required to contact other parts (such as a fuel tank), the method of sandwiching the rubber can avoid the collision noise caused by the vibration and improve the oil blocking effect.
The vacuum pump that rotates the gas into, compresses and discharges, such as the reciprocating vacuum pump , the rotary vane vacuum pump , the slide valve vacuum pump , and the Roots vacuum pump , causes the noise to a great extent from the abrasion of the piston. Avoid running vacuum pumps near maximum vacuum or maximum discharge pressure. Operating in this area is not only inefficient, but also very unstable and prone to vibration and noise. For vacuum pumps with higher vacuum, cavitation often occurs in this area. The obvious sign of this phenomenon is noise and vibration in the pump. Cavitation can cause damage to the pump body, impeller, etc., and the water pump cannot work. According to the above principle, when the required degree of vacuum or gas pressure of the water pump is not high, it can be preferentially selected in a single-stage water pump. If the vacuum level or discharge pressure is high, single-stage pumps are often unable to meet, or require the pump to still have a larger volume of gas under higher vacuum conditions, that is, the performance curve is required to be flat at higher vacuum levels. Water pump. If the vacuum degree is above -710mmHg, water ring-atmospheric water pump or water ring-Roots vacuum unit may be used as vacuum pumping device.
In addition, an oil-free scroll vacuum pump can also be used to reduce noise. The compression process is relatively slow, there are two or three compression processes at the same time, the compression chamber is symmetrical with respect to the crankshaft, so that the pump running process is smooth, driving torque and gas shock fluctuations are small, so that the noise and vibration of the water pump are reduced.
Anlet Rucker vacuum pump can be widely used in vacuum drying, food vacuum packaging, solvent gas recovery, carbon dioxide gas recovery, vacuum forming, vacuum concentration, vacuum deaeration, central vacuum system, vacuum heat treatment.
[16] Several Problems to Be Paid Attention to When Using Water Pumps
Correct use of the method is an important factor in prolonging the life of water pumps and reducing economic losses.
(a) For submersible pumps
Before starting, some necessary inspections should be done: whether the rotation of the water pump shaft is normal, whether there is a stuck phenomenon, whether the position of the impeller is normal, and whether the cable and the cable plug have cracked, scratched or broken. Pay attention to observe the change of voltage during operation, generally control within ± 5% of rated voltage. In addition, the position of the water pump in the water is very important. It should be possible to choose a place where there is plenty of water, no silt, and good water quality. It should be suspended vertically in the water, and it must not be placed horizontally to avoid being trapped in the mud or blocked by the suspended water. , Which led to a sharp drop in the amount of water or even no access to water.
(b) For self-priming pumps
It should be placed in a well ventilated place as much as possible to facilitate rapid heat dissipation and reduce motor temperature. Otherwise, long-time operation can easily burn the motor. If a farmer is using a self-priming pump, it will not remove the plastic film covering the motor, causing the motor to overheat and burn out the coil. In addition, before starting, be sure to check the amount of water in the pump body, otherwise it will not only affect the self-priming performance, but also easy to burn the shaft seal components. Under normal conditions, the water pump should be turned off 3 to 5 minutes after it starts. Otherwise, it should be stopped immediately.
(three) pump maintenance
When the water pump fails, do not remove it yourself. When dismantling oneself, one does not know where the fault is, causing blind disassembly; the second is that there are no special tools and often damage the original spare parts. The best way is to go to an experienced, large-scale maintenance point repair and replace “overage†parts and certain wearing parts in time. Under normal circumstances, the water pump should be repaired every six months to eliminate the "disease" work.
(D) Storage during non-use period
In the non-use period, the water pump should be lifted off the water source in time, and the water in the water pump should be drained, especially in the cold winter. Then place it in a dry place. Conditional users can also apply butter to the key parts of the water pump, and lubricate the bearings to prevent corrosion. In addition, the non-use period of the water pump is not as long as possible. If you do not use it for a long time, it will not only easily rust parts, but also reduce the service life of the water pump.
Pump Selection General Procedure
1, according to the layout of the device, terrain conditions, water level conditions, operating conditions, economic plans and other factors
2, consider the choice of horizontal, vertical and other types (pipeline, right angle, angle, angle, parallel, vertical, vertical, submersible, removable, submerged, non-blocking, Self-priming, gear, oil-filled, and water-filled. Horizontal water pump is easy to disassemble and assemble, 3, easy to manage, but bulky, 4, price is more expensive, 5, need a lot of floor space; vertical pump, 6, in many cases the impeller is submerged in water, 7 can be Start, 8, easy to automatically or remotely control, 9, and compact, 10, small installation area, 11, the price is cheaper.
3, according to the nature of the liquid medium, determine the clean water pump, hot water pump to oil pump, chemical pump or corrosion resistant water pump or contaminated water pump, or use non-blocking water pump.
Pumps installed in explosion areas should be explosion-proof motors based on the level of the explosion zone.
4, vibration is divided into: pneumatic, electric (electrically divided into 220v voltage and 380v voltage).
5, according to the size of the flow, the menu suction pump or double suction pump: According to the level of lift, menu or multi-absorbent suction pump, high speed water pump or low speed water pump (air conditioning pump), multi-stage pump efficiency lower than single-stage pump, when the menu When a grade pump and a multi-stage pump can all be used, a single-stage pump should be used.
6, to determine the specific type pump, using series after what the selected pump, according to the maximum flow rate can be enlarged 5% - 10% of the balance after lift performance of these two main parameters, on the type or series of characteristic spectrum Determine the specific model.
Using the pump characteristic curve, find the required flow value on the abscissa and find the desired head value on the ordinate. Direct the vertical or horizontal line from the two values ​​upwards and to the right. The intersection of the two lines falls exactly on the characteristic curve. The pump is the pump to be selected, but this ideal situation is generally not very small, usually encounter the following situations:
A. First, the intersection point is above the characteristic curve. This shows that the flow rate meets the requirements, but the lift is not enough. At this time, if the heads are almost the same, or the difference is about 5%, they can still be used. If there is a lot of head difference, the head selection is larger. Water pump. Or try to reduce pipeline resistance loss.
B. Second: The intersection point is below the characteristic curve. Within the fan trapezoidal range of the pump characteristic curve, this model is preliminarily set, and then according to how much the head difference, to decide whether to cut the impeller diameter. If the head difference is small, it will not cut. If there is a big difference between the lifts, press Q, H, and , depending on their ns
And cutting formula, cutting the diameter of the impeller, if the intersection does not fall within the scope of the fan-shaped trapezoid, should choose a smaller pump.
When choosing a water pump, it is sometimes necessary to consider the production process requirements and choose different QH characteristic curves.
A. For example, to convey the liquid level to a container that must maintain a certain liquid level,
B. At this time, change
C. There is a big change in the prospects, and
D. The head change is very small.
E. The pump with flat HO curve should be used as the secondary pump.
F. It is like: sending oil to a tube furnace,
G. If the flow changes little at work,
H. The coking phenomenon is likely to occur in the furnace tube. To avoid this situation,
I hope but when the flow decreases slightly,
J. The pressure on Guanzhong oil has increased significantly.
K, so that the eschar that is about to be formed is flushed away by the high flow pressure,
L. At this time,
M, should choose the QH curve is slightly lower oil pump.
7. After the model of the pump is determined, the water pump or the pump that transports the physical and chemical medium close to the water needs to go to the relevant product catalog or sample and correct it according to the model performance chart or performance curve to see if the normal working point falls. The pump has priority work area? Whether the effective NPSH is greater than (NPSH). Can also be reversed to NPSH correction geometry installation height?
8. For liquid pumps with transmission viscosities greater than 20 mm2/s, it is necessary to convert the characteristic curve of the water test pump into the performance curve of the viscosity, in particular, to carefully calculate or compare the performance of the suction.
9, determine the number of pumps and standby rate:
Normally only one pump is used for normal operation. Because a large pump is equivalent to two small pumps working in parallel (refers to the head and flow), the efficiency of large pumps is higher than that of small pumps. Taida pumps do not use two small pumps, but in the following cases, two pumps can be considered in parallel:
The flow rate is very high and a water pump cannot reach this flow.
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