Seal packing precautions before installation , how to choose a suitable packing

A seal packing precautions before installing what ?
Sealing Packing Precautions before installation :
Remove old packing stuffing box is pre- installation inspection to prepare the point.
With the old filler filler before the first use special tools to remove all the stuffing box clean
Observe the various parts of the stuffing box without injury eccentricity defects , damage of the stem, bushings and packing stuffing box can affect performance.
Check whether other components can also be applied . Replace all damaged parts .
Second, how to choose a suitable packing ?
How to choose the right packing ? Packing in the selection must take into account two things.
① conditions required performance should be consistent with the packing . According to the relevant technical data to select the most able to meet the requirements of packing.
② sealing requirements must be based on the correct choice packing size. To determine the cross-section ,fixed length plastic strap seal please use the following formula estimates:
Cross-section = ( stuffing box diameter - stem diameter ) / 2
The apparatus of injury may need a larger cross-sectional packing, in order to compensate for damage.
Third, cutting and sealing packing installation pay attention to details
Cutting and sealing packing installation pay attention to details
1 , select the appropriate packing, mechanical precision cut by cutting the required length of the packing ring , without packing cutting machinery, in accordance with packing length L = ( D + packing shaft width S) X1.07X Ji to cutting, generally rotary shaft , a 90 ° straight cut, the valve with a 45 ° cut . Never tried to surround the stuffing box packing to determine the length . Or the packing around the stem with the same . Of a tube, it firmly suppressed, but not stretched packing. Then cut into sample loop , and verify whether it can properly fill the space , and to ensure there are no gaps at its interface . Then be used as a standard sample loop cutting other packing rings . If the finished product on a flat surface finish , soft or easily deformed if the packing can be produced according to a small sample loop tape , and talking under the rope to make the rest of the packing rings .
2, when packing for the valve, tamper evident tapes the valve packing section and the same space , it is best to preload ring: When used in pump, valve packing section and space ( approximately 0.3MM-0.6MM) and the shaft packing has a leak gap in favor lubrication and cooling .
3 , first install a filler ring , make sure no glue each filler dust or other debris . If needed, packing ring on the stem should be the same with the use of clean oil to lubricate . Staggered placement of each packing ring into 90 °. Ring in the axial slowly opened.