Products
API Plan 52
API Plan 52
Reservoir providing buffer liquid for the outer seal of an arrangement 2 unpressurized dual seal. The buffer liquid shall be maintained at a pressure less than seal chamber pressure and less than 2.8 bar (40 PSI).
A From mechanical seal
B To mechanical seal
C Filling connection
D Cooling water IN
E Cooling water OUT
F Drain
G Connection to flare
Seal chamber details
4 Flush (F)
5 Liquid buffer OUT (LBO)
6 Liquid buffer IN (LBI)
11 Seal chamber
Example seal: EagleBurgmann H75A4-T dual pusher mechanical seal.
P&ID according to API
Key
1 To collection system
2 Reservoir
3 Make-up buffer liquid
7 Cooling water IN
8 Reservoir buffer fluid drain
9 Cooling water OUT
10 Buffer fluid drain
LI Level indicator
LIT Level transmitter with local indicator
Features
- Provides lubrication and cooling to the contacting wet outboard safety backup seal.
- The pumped fluid will not become contaminated.
- The pumped media does not leak directly to atmosphere.
- No pressurization required for the reservoir as is case of a Plan 53A.
- Provision of cooling coil inside the reservoir or an external water or air cooler takes care of the heat removal.
- Uses an internal circulating device to ensure buffer liquid circulation.
Application
- For flashing services – for example light hydrocarbons, high vapor pressure fluids. Can also be used for non-flashing services.
- For services where product contamination by a barrier fluid is not acceptable
Remarks, checkpoints
- Do not use for contaminated and polymerizing media.
- Use a restriction orifice plate in the vent line to maintain a back pressure in the reservoir.
- Vent the system before start-up. Later ensure that the vent line always remains open and is connected to the flare.
- The piping from the seal to the reservoir should be self-venting.
- Sense the seal inlet and outlet line temperatures. Difference in the temperatures is an indication of proper flow.
- An increase in either the reservoir pressure or reservoir level is an indication of inboard seal leakage.
- A decrease in the reservoir level is an indication of outboard seal leakage.
- Ensure the compatibility of buffer liquid with the pump media.
- The buffer liquid shall be maintained at a pressure less than the seal chamber pressure and less than 2.8 bar (40 PSI).
- Check buffer liquid quality at regular intervals and replace if required.
Pump media characteristics
- High vapor pressure, flashing media.
- Clean, non-polymerizing.
- Hazardous / environmentally harmful if leaked directly to the atmosphere.
Location, function
- Between seals
- Buffer system (psealchamber > pbetweenseals)
- Lubrication and flushing for the outboard seal and cooling for inboard as well as outboard seals.
Configurations
2CW-CW
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