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التفكير المنطقى لحل مشاكل الطلمبات
دائما عند حدوث اعطال او كسر فى اى من اجزاء الطلمبه او المضخه يتم تغير الجزء الموجود به الكسر او العطل دون النظر فى معرفة السبب وهذا يؤدى الى تكرار العطل على فترات قصير لذا يجب عند حدوث عطل او كسر فى احدى اجزاءها عمل تحليل كامل وراء الاعطال ومعرفة سببها وهناك عدة خطوات ينصح بها خبراء المضخات حول العالم لتحليل الاعطال وهى
1.     
Ask ‘What’s making this happen?’ - It is likely that what we call the problem is actually the symptom. Example: ‘Low discharge pressure’, ‘failed mechanical seal’, ‘the pump makes noise.’
بمعنى ما هو العطل مثال اذا كان هناك مشكله مثل وجود اصوات عاليه عند عمل الطلمبه  او لايوجد سحب او لا يوجد خرج ( discharge ) تحديد المشكله اولا.
2.      Look for the evidence - The evidence is the manifestation of the symptoms. The evidence indicates that there is a problem with the pumping system. Example: ‘the discharge gauges indicate a low pressure’.
يجب وجود دليل على المشكله مثال اذا كان الضغط التوزيع قليل اذن لابد ان يكون قراءة مؤشر عداد الضغط منخفض عند خرج الطلمبه
3.      Verify evidence - Example: ‘Is the gauge calibrated and accurate?’ Eliminate or cancel other reasons or possibilities for the evidence. Example: ‘The pump is not pumping enough pressure and we’re no longer able to fill that tank.’
عن طريق وجود الدليل على العطل يتم تحديد الحل المشكله مثال اذا كان هناك ان قراءة مؤشر عداد الضغط منخفض هل تم معايرة العداد فقد يكون العيب فى العداد نفسه ام ان ضغط الخروج قليل ولا يستطيع ملئ الخزان  
4.      Identify the causes supporting the evidence. Example: What could cause low pressure? The cause is the origin of the failure.
اذكر الاسباب المتعلقه بالمشكله او الاسباب التى تؤدى الى مثل هذا العطل على سبيل الحصر واليكم مثال على وجود مشكله بالطلمبه وكيفيه تحديد المشكله وتحديد الحل
The causes of low pressure, for example, could be either hydraulic or mechanical. In many cases of failure analysis, asking ‘Why?’ and ‘What?’ and answering those questions, until you can no longer ask ‘why’, will almost always get you to the answer. If all evidence leads to a mechanical reason for the failure, the problem is probably maintenance induced. If the evidence leads to a hydraulic reason for the failure, the problem is either operations or design induced. In cases where the ‘reason for failure’ was not determined, a more extensive analysis is necessary. The additional analysis is recommended to take advantage of the pump supplier experience in identifying the root cause.
مثال اخر على اعطال الطلمبه سخونه وكسر فى رمان البلى  
A paper mill was using an ANSI end suction process pump with clear water service. The motor was designed properly. The pump axial thrust bearing ran hot, failing after three months of operation. It was replaced with an identical bearing. This ran during three months and also failed. All pump components where investigated and found that they complied with the specifications these facts eliminated the defects of materials as a cause.
 The most common problems in centrifugal pumps اشهر اعطال الطلمبه واسباب حدوثها وكيفيه حل مشاكلها

Symptom  (complains )
Possible Hydraulic Cause
Possible mechanical cause

Noisy Pump.
Cavitation
Aspirated Air
Excessive Suction Lift
Not enough NPSHa
Bent Shaft
Bound Rotor
Worn Bearings


Not enough discharge
Flow
Excessive discharge Head
Not enough NPSHa
Worn or damaged impeller
Inadequate foot valve size.
Air aspiration or air pocket in the suction line.
Plugged impeller or piping


No discharge pressure.
Pump improperly primed.
Inadequate Speed.
Not enough NPSHa.
Plugged impeller or piping.
Incorrect rotation.
Closed discharge valve
Air aspirated or air pockets at the suction line.

Pressure Surge.
Not enough NPSHa.
Air aspirated or air pockets at the suction line.
Entrained Air.
Plugged impeller.

Inadequate Pressure.
Not enough velocity.
Air or gases in pumped liquid.
Impeller diameter too small
Worn or damaged impeller
Incorrect rotation


Excessive Power
Consumption
Head too small, excess flow.
High specific gravity or high viscosity.
Bent shaft.
Bound shaft.
Incorrect rotation

The most common problems of positive displacement 

Problems
Source of problem
Suggested causes


Pump fails to 

discharge 

liquid


Suction problem
Suction pipe not 

submerged, 

clogged strainer, 

foot valve leaks, 

suction lift too high  

and air leak in 

suction piping,

System problem
wrong rotation and low speed


Noisy pump
Suction problem
Air leaks in suction piping,



System problem

Insufficient liquid 

supply, Excessive discharge pressure /resistance



Mechanical problems

Unbalanced or 

misaligned 

coupling, Bent 

motor shaft, 

Chattering relief 

valve and Pipe 

strain distorting the 

pump casing



Pump wears 

rapidly


System problem

Excessive 

discharge pressure 

/resistance, Grit or 

dirt in liquid, Pump 

running dry



Mechanical problem

Unbalanced or 

misaligned 

coupling, Air 

aspiration thru the 

packing/sea, 

Corrosion



Pump not up 

to capacity


Suction problem

Clogged strainer, 

Suction lift too high, Air leak in suction piping, Suction piping too small
System problem
Low speed

Mechanical problem
Inadequate relief 

valve, Packing is 

too tight.


Pump starts,

 and then 

loses suction


Suction problem
Not properly primed, Suction pipe not submerged,  Air leak in suction piping, Suction piping too small
System problem
Insufficient liquid supply


Pump

 consumes

excessive

power

System problem
Viscosity of liquid being pumped is higher than specified


Mechanical problem
Unbalanced or 

misaligned 

coupling, Air aspiration thru the packing/sea, Bent motor shaft

2 comments:

Mohammed Abdu يقول...

الله ينور يا باشمهندسة فاطمة

غير معرف يقول...

الله يبارك ليكم العمل الجميل دا

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