المواضيع الاكثر مشاهده
2:48 ص | Posted by
f_abady |
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 |
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