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I N S T A L L A T I O N , O P E R A T I O N A N D M A I N T E N A N C E M A N U A L
7.2. WEAR RING DETAILS.
Pumps are supplied with casing wear rings. The diametrical clearance between impeller
and casing rings should be minimum 0.25 mm and maximum 0.70 mm.
7.3. IMPELLER DETAILS
Following pump types are fitted with single entry impeller DP 50/30 A, DP 50/0B, DP 80/38,
DP 65/38 and DP 65/38 M.
For other types, Double entry impellers are fitted.
7.4. COUPLING DETAILS
Pumps will be supplied with snap wrap coupling as s standard scope of supply. However
other types like pin bush, tyre, spacer coupling can also be providing on request.
7.5. MINIMUM SAFE FLOW
The pump should not run against closed discharge valve as this will cause an increase in
temp/formation of steam in the pump. This may cause shaft damage, impeller erosion,
short life of bearings and damage to stuffing boxes or mechanical shaft seals due to stress
or vibration. The minimum flow rate must be at least 30% of the best efficiency point flow
rate.
7.6. NPSH A (NET POSITIVE SUCTION HEAD AVILABLE) AND NPSH R V(NET
POSITIVE SUCTION HEAD REQUIRED)
NPSH A available should be at least greater than 0.5 m than NPSH R for satisfactory
operation of the pump. If NPSH A < NPSH R then pump cavitations may occurs which in
turns damage the impeller.
7.7. PIPE LINE VELOCITIES.
For satisfactory operation of pumps and to minimize frictional losses, it is recommended to
maintain velocity in suction pipe line as 1.5 to 2 m/s and in delivery line it should be 2.5 to 3
m/s by providing higher pipe diameter than pump suction / delivery size.
7.8. TAPPING DETAILS.
SL NO
1
2
3
4
5
19 |
P a g e
TAPPING DESCRIBTION
Air Vent
Priming connection(Plugged)
Sealing connection
Suction and Delivery Gauge
Connection(Plugged)
Casing Drain
SIZE(INCH)
3/8 BSP
1/2 BSP
3/8 BSP
3/8 BSP
1/2 BSP
D E C C A N I N D U S T R I E S
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