Recommendations for installation of mechanical seals
For details, we strongly recommend you look in the instruction for installation and operation of mechanical seals various types. Here are just some general guidelines for the installation of seals.
Preparing for installation:
- mounting seal must have the installation and operation, as well as the corresponding drawing;
- before starting to check the dimensions and the corresponding maximum tolerances, including tolerances specified shapes and arrangements;
- all edges and piles on which is mounted the mechanical seal should be cleaned, rounded and have a chamfer not exceeding 30 ° x 2 mm;
- deviations of linear and angular dimensions must comply with the tolerances DIN ISO 2768;
- quality surface treatment must conform to EN 12756 (DIN 24960).
It is necessary to remember that the tolerance of edge beat depends on rotating speed.
Resistance to the extrusion of elastomeric circular rings, can be substantially increased by using support rings.
Radial runout of the shaft or the shaft protection sleeve in the contact surfaces of the mechanical seal diameters < 50 mm should not exceed - 50 microns, for diameters of 50 to 100 mm - 80 microns and diameter > 100 mm - 100 microns, in accordance with DIN ISO 5199.
When the slip speed < 25 m/s misalignment seal chamber with respect to the shaft should not exceed - 200 microns and when using the internal impeller of the influence on the flow characteristics - 100 microns. For sliding speed > 25 m/s with the lowest value.
The main principle of the mechanical seal assembly is the maximum purity and thoroughness of execution.
Pollution and damage to the sealing surfaces and O-rings are reflected in the durability of seals.
Protective coatings sliding surfaces must be removed without residue.
Never apply grease to the sliding surface should be completely dry before installation, remove dust and mud.
It is necessary to follow precisely the enclosed mounting instructions, and also instructions on drawings.
Before installing the seal on the shaft or seal cartridge in the chamber to reduce frictional forces necessary to apply a thin layer of silicone grease or oil on the O-rings. Attention! Do not apply for the seals with elastomer bellows.
O-rings of the ethylene-propylene rubber in any case must not come into contact with mineral oil or grease. Installation/indentation counter rings should protect sliding surfaces, follow the uniform distribution of pressure and efforts to lubricate O-rings to reduce friction with water only or alcohol.
In the absence of a special clamp screw connection, prior to installation on the set screws after removal of grease should be applied a suitable adhesive (eg, Loctite).
Mechanical seals of NM series with elastomer bellows should be fitted on the shaft pre-moistened or ordinary soapy water (with the addition of surfactants). Well moisten a bearing surface and shaft seals. Moisten more often if large distance by which to move the seal. Attention! Do not use oil or grease!After installation is complete, check the correctness and tightness of the ring L-shaped cross-section, the spring, and the movable rings.
When installing the mechanical seals of NMM series on the shaft, axial force shall be applied to the bellows holder. Do not flatten the metal bellows seal. When installing the ring shaped section NMM-GR, consider the following:
- ring must be inserted only in the dry state and in the axial direction (radial deformation leads to fracture);
- shaped section of the ring with the counter ring must be evenly pressed into the receptacle (taking into account the tolerance of alignment);
- screws on the rotating assembly should be tightened in sequence (not diagonally) over several passes, leaving behind uniform gap possible.
To prevent damage to the sliding surfaces with dry friction, after the seal assembly must be carefully removed from the air space of the gate. This is especially important for those systems in which the air is completely or partly may not exceed naturally, for example, with double sealing of the closure pressure settings.