First, key mounting technique of centrifugal pump
The key to the centrifugal pump mounting technique of the pipeline confirms the rivers state after the water pump pipeline forms a complete set. And water pump it installs height to be should to allow, suck upper vacuum, deduct, absorb water pipeline lose after the lift highly, make the share of number value, the height that it should overcome the real shape to absorb water lastly. The water pump installation height can’t exceed the calculating value, otherwise, the water pump can not release Sheung Shui to come. In addition,influence there aren’t pipeline resistance after absorbing water to calculating size,it should adopt pipelines shortest not to be assigned, and try hard to install few curved first class fittings, can also consider that mix large some bore water pipe appropriately, in order to reduce the velocity of flow in the tube.
Should point out, when pipeline centrifugal pump mounting point high Cheng and water temperature are different from the experimental condition, will draw water 300 meters above sea level water temperature exceed 20 ℃, person who calculate need, go on, revise. Namely different the atmospheric pressure of high Cheng place above sea level the vaporized pressure of the saturation when and higher than 20 ℃ water temperature. ,The water temperature, in order that at the time of under 20 ℃, the vaporized pressure of the saturation can be ignored.
From the installation of pipeline technically, absorb water the pipeline demands to have sealing nature strictly, can’t leak gas, leak, otherwise destroy the water pump and enter water mouth vacuum degree, will make the water pump yield reduce, can’t release Sheung Shui to come when being serious. ,Do a good job of interface of the pipeline conscientiously, guarantee the pipeline connects the construction quality.
Second, height Hg of centrifugal pump installation are calculated
It means pressure p1 can allow to reach the maximum vacuum degree at the pump entrance to allow to suck the upper vacuum height Hs.
And allow to suck upper vacuum height Hs value and type calculating value actually, by pump manufacturer’s experiment measured value, this value is attached to the pump sample for users to check to use. Should notice that it is to use the fresh water to be a job medium to provide Hs value in a pump sample in the location, it is that 20 ℃ and and pressure is 1.013* 105Pa duration to operate the condition, when it is different to operate conditions and job mediumsing, need to convert.
1Transport the fresh water, but operate the condition different from experiment condition, can convert in accordance with the following formula
Hs1 =Hs Ha- 10.33 -Hυ – 0.24
2Transport other liquid as transport into liquid and the intersection of villain and terms and experiment terms not simultaneously, need to convert two steps: In accordance with have type, find Hs1 in the intersection of pump and sample first; Second step convert Hs1 into H% 26# 900 in accordance with the following formula; s
Surplus Δ h that 2 vapour loses
Oil pump, calculate install height, losing with vapour the intersection of surplus and the intersection of Δ and h come on, calculate, pump allow, suck the intersection of liquid and vacuum degree, namely the pump allows to install the height, the unit uses the rice. Lose with vapour the intersection of surplus and the intersection of Δ and h consult, fetch in the intersection of oil pump and sample, its value is determined with 20 ℃ fresh water too. If transport other liquid, also need to correct, the relevant books of detailed survey.
Suck Cheng =Standard atmosphere 10.33 meters -Vapour lose surplus – safe quantity ‘ 0.5 meters
The standard atmosphere can pigeonhole the pipeline vacuum height of 10.33 meters.
For example: The surplus is 4.0 meters that some pump essential vapour loses, are asked and sucked Cheng Δ h?
Solve: Δ h =10.33-4.0-0.5 =5.83 meters
Consider from the safe view, install the high value and should be less than the calculating value actually with pump. When Hg that calculates is the negative value, prove the pump sucks the position of port and should be stored under the level surface of trough.
The example 2-3 some centrifugal pump checks that allow to suck the upper vacuum height Hs from sample =5.7m. Know, suck pipeline all resistance 1.5mH2O, as atmosphere pressure being 9.81* 104Pa, liquid suck in the pipeline moving, pressing hair, can neglect already. Try calculating:
1The pump is installed while transporting 20 ℃ fresh water;
2Install the height with pump while switching over to transporting 80 ℃ water.
Solve: 1Install the height with pump while transporting 20 ℃ fresh water
Have already known: Hs =5.7m
Hf0-1 =1.5m
U12/2g≈ 0
Test the condition when atmosphere pressure is 9.81* 104Pa, dispatched from the factory with the pump and basically conform, it is Hg to install the height with pump =5.7-0-1.5 =4.2m.
2The installation of pump highly sends 80 while transporting 80 ℃ water