Is it good to use a mechanical seal on the oil pump?
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In the project I’m working on currently, there are many oil pumps used for transporting waste oil. In some of these pumps, the mechanical seals burned out after just a few days of use; the high temperatures caused the sealing rings of the moving parts to be damaged, and as a result, oil started leaking from the area where the mechanical seals were located once the oil inlet was opened. I would like to ask whether mechanical seals are suitable for use at a rotation speed of 2900 revolutions per minute. What is their typical lifespan? Several units have already failed, which is quite confusing for me.
There are two suspected reasons for the burnout of the seal in the waste oil pump: one is too high a temperature, and the other is wear caused by solid impurities in the waste oil entering the seal. The solutions are essentially two-fold: providing circulating cooling for the mechanical seal, and adding a clean oil flushing line for it.
A mechanical seal should be used on the oil pump, as packing is more prone to leakage. Solution: 1. Adjust the compression amount of the mechanical seal. 2. Used oil may contain solid particles; therefore, add an additional line of sealed flushing oil – diesel can be used, with the pressure being about 0.4 MPa higher than that in the sealed chamber. 3. Vibration of the pump causes seal leakage. Measure the vibration of the pump; adjust its alignment so that the vibration level is below 4 mm/s. Excessive vibration in the pump can lead to seal leakage. For a pump used for transporting waste oil like yours, the vibration level should be around 1.5. I hope the above methods will help you resolve the issue soon. Contact us if you have any questions.
The use of mechanical seals in oil pumps is a very common practice; however, the selection of such seals must be appropriate for the respective temperatures and pressures. For applications that may contain solid particles, there are many flushing options available in the API610 standard. Additionally, when installing a mechanical seal, it is important to adjust the compression amount properly and avoid creating a vacuum during operation. In principle, only a flushing medium can be present between the sealing pairs, and no conveying medium
I recommend using steam sealing, as it is reliable and long-lasting.
The use of mechanical seals for oil pumps has always been a challenge in China. One reason is the high temperatures, and another is that the mechanical seals operate under quite harsh conditions; in such cases, bellows-type mechanical seals are required. If the pressure is high, double-layer bellows mechanical seals should be used, and PLAN23 and PLAN62 can effectively solve this problem. However, if the oil pump operates intermittently, the waste oil must be replaced with diesel before stopping the pump, or the pump must be kept warm continuously.
This is good; I’ve never seen it before. Could you explain it in detail?
Steam sealing is generally not used alone. For oil pumps, using steam sealing alone can easily lead to cavitation in the pump. The steam seal is generally arranged outside the flushing oil seal. In this way, flushing oil can be used to keep the seal ring clean, while steam can be used on the outside to ensure that any leakage consists only of clean steam.
Pay attention to the usage and installation conditions, 1. Check for alignment and eliminate the issue of uneven wear ； 2. Should the pump be started before turning it on? ； 3. Rule out issues with the shaft surface finish at the machine seal installation site ； Our oil pumps all use mechanical seals, and the performance is quite good ；
Mechanical seals used in oil pumps generally meet the requirements. It’s indeed abnormal for the device to burn out as frequently as the poster mentioned. First, check whether the technical parameters of the pump meet the requirements of the operating conditions. If that can be satisfied, then look for the cause in the installation and adjustment of the pump and mechanical seal. Do not overlook the quality issues of pumps and mechanical seals as well. If it cannot be met, then find ways to solve the specific problem. For example: adding a flushing medium to the sealing pair, etc.
Firstly, it is closely related to the use of mechanical seals; most cases of damage to these seals are caused by improper use. Secondly, there is a significant difference in quality among manufacturers of mechanical seals. For domestic brands, I recommend Dandong Klon and Sichuan Niki. Thirdly, if mechanical seals are not suitable, it is advisable to use bellows seals instead.
If the seal is damaged, it is necessary to check the oil temperature; if it exceeds 200°C, a metal bellows can be used for the mechanical seal, while flexible graphite can be employed as an auxiliary seal. If there are particulate impurities in the oil, an alloy can be used as the friction pair.
If the seal is damaged, it is necessary to check the oil temperature; if it exceeds 200°C, a metal bellows can be used for the mechanical seal, while flexible graphite can be employed as an auxiliary seal. If there are particulate impurities in the oil, an alloy can be used as the friction pair.
Actually, this involves the selection of equipment, and the parameters for such selection are head, flow rate, operating temperature, and the type of medium. After reading all the responses, I think the answer provided by the user on floor 6 is correct, with the additional points from floor 13 being useful as well. I would also like to ask the experts here: when the medium may contain solid particles and the operating temperature is 270 degrees, with moderate requirements regarding head and flow rate, is it possible to use a screw pump? What precautions should be taken? PS: I don’t have in-depth knowledge of screw pumps. Hehe
Using a single-face mechanical seal with external flushing eliminates the problem; however, there may be some losses.
High temperature – isn’t the seal cooled?
Using a mechanical seal works well. Depending on your situation, you can opt for a hard-to-hard seal or a bellows seal; in addition, external flushing can be used, and cooling water can be added to the water jacket in the sealing chamber.