Affecting points the selection of mechanical seal .

1. Globe Star Engineers (India) Pvt. Ltd.
Manufacturer, Exporter and supplier of mechanical seal, Rotary Joint
and All types of Pump
PRESENTS
“FACTORS AFFECTING THE SELECTION OF MECHANICAL SEALS”

2. 1. Media Handled :
Corrosiveness of media decides the material of construction.
• Density of viscosity shows the lubricating properties of the
media. This decides the seal arrangement.
• Abrasives in the media decides the type of flushing plan
required Corrosiveness of media decides the material of construction.
• Density of viscosity shows the lubricating properties of the media. This
decides the seal arrangement.
• Abrasives in the media decides the type of flushing plan required.
2. Stuffing box pressure :
• When stuffing box pressure < 10 kg. / cm2, unbalanced seals are used.
• When stuffing box pressure . 10 Kg. / cm2 , balanced seals are used.
3. Shaft Speed :
• With increase in speed the chance of seal running dry increases. So
proper
flushing plan has to be decided which can give positive flush between the
faces.
4. PV Factor :
• PV factor is defined as the product of the pressure drop across the seal
and
the average rubbing velocity. As a general guide, Seal capabilities can be
classified as, Low , if the PV value is 0.7 MPa m/s ( about 20,000 psi ft/min)
Medium, if the PV value is between 0.7 and 10 MPa m/s ( about 285,000 psi
ft/min) High , if the PV value ranges from 10 to 70 MPa m/s (about 2,000,000
psi
ft/min). Balanced seals reduce the pressure acting on the seal faces,
therefore they have higher PV values than unbalanced seals.

3. 5. Temperature :
• This decides the material of construction so that the seal does not fail at
operating temperature.
• This will decides the seal flushing plan.