Liquid Compressant (Seal Water) - NES NBE Series Operation & Maintenance Manual

For different types of mechanical seals and their
respective sealant supplies, the following steps should
be taken during commissioning:
1. Single-Acting Mechanical Seal with Internal Sealant
Supply:
Before starting the pump confirm that the interior of
the machine is filled with operating Liquid
approximately up to the shaft center. This prohibits
the mechanical seal from running dry.
2. Single-Acting Mechanical Seal with External
Sealant Supply:
Shortly before starting the machine opens the shut-off
fitting for the sealing liquid. This prevents drying of
mechanical seal and maintains the liquid level in the
machine at an appropriate level.
3. Double-Acting Mechanical Seal:
Just before starting the machine, open the shut-off
valve for the sealing liquid. This will stop the
mechanical seal from running dry.
4. Adjustment of Volumetric Flow or Feed Pressure of
Flushing/Sealing Liquid:
Use a volume flow meter or a pressure gauge to check
and adjust the values of the flushing or sealing liquid.
This ensures that the desired volumetric flow or feed
pressure is maintained.
It is important to carefully follow the specific
instructions provided by the manufacturer for the
mechanical seal and sealant supply configuration of
your machine. These steps help prevent the
mechanical seal from running dry, ensuring its proper
functioning and longevity.
Type Shaft Seals
NBE3/4... - ... 3 Stuffing box with external
liquid feed (external sealant
supply)
NBE3/4... - ... 4 Stuffing box with external
liquid wetting (standard)
NBE3/4... - ... Mechanical seals
5...9
Table 1: Types of mechanical shaft seals
NBE O & M Document No. NES/NBE/O&M

5.2 Liquid Compressant (Seal Water)

The operating Liquid, often referred to as the sealing
Liquid or liquid compressant, plays a crucial role in
the operation of liquid ring machines like vacuum
pumps and compressors. It helps create a liquid ring
within the housing, which acts as a seal between the
impeller and the housing, preventing direct contact
between the gas being handled and the impeller. The
sealing fluid is typically fresh water at a temperature of
60F. Refer to table 2. below for seal water flow rate
information. Alternatively, other fluids such as diesel,
mineral oil, and methanol can be used as sealing fluid
depending on the process requirements and
availability. When using a discharge separator, it is
important to ensure that the seal fluid level always
remains below the centerline of the pump during
Operation. This prevents any back pressure caused by
the discharged seal fluid.
WARNING!
When working with hazardous gases or operating liquids,
it is imperative to prevent any unintended escape of gases
or operating fluids in the event of an unforeseen reduction
in seal function. This can be achieved by employing
appropriate shaft sealing methods, such as mechanical seals
with external supply, to ensure the integrity of the system.
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