Answer EKG Question 8
Q8. With reference to Vacuum Sewage System:
(i) Sketch & Describe a Vacuum Sewage System.
(ii) State the advantages of Vacuum Sewage System.
(iii) State the different causes of dropping vacuum.
Answer:
(i) Sketch & Describe a Vacuum Sewage System.
The sewage treatment unit product consists of biological and physical/chemical based treatment. The sewage treatment units are designed to work together with the vacuum collecting units
Vacuum piping components such as vacuum interface valves, non-return valves, air valves and chemical dosing units.
Grey water collecting units/pump stations
For galley and kitchen waters there is available an integrated grey water collecting unit and a grease separator which saves space and simplifies the system.
Grease separators
Galley and kitchen water contain grease which is harmful for a piping system and a treatment process.
(i) Sketch & Describe a Vacuum Sewage System.
(ii) State the advantages of Vacuum Sewage System.
(iii) State the different causes of dropping vacuum.
Answer:
(i) Sketch & Describe a Vacuum Sewage System.
The vacuum toilet system uses vacuum for sewage transport from sanitary
fixtures, like toilets, to a sewage collection tank in small diameter
sewage piping not depending on gravity.
Vacuum can be created by sewage powered ejectors, or vacuum pumps.
Vacuum toilets, connected to the piping system, use only 0.6 to 1.2
liters of water per flush Rinse water valve, discharge valve and control
mechanism are integrated into the toilet bowl.
Other
sanitary fixtures like urinals, wash basins, shower trays and bath tubs
operating with gravity principle are connected to the vacuum system via
vacuum interface valves.
In vacuum collecting units vacuum is created with ejectors or with vacuum pumps. When ejectors are used, different flexible collection configurations can be utilized; pre-assembled acid proof tank units, shipyard built tanks or combined units where vacuum creation and biological treatment is builtin in the same unit.
In vacuum collecting units vacuum is created with ejectors or with vacuum pumps. When ejectors are used, different flexible collection configurations can be utilized; pre-assembled acid proof tank units, shipyard built tanks or combined units where vacuum creation and biological treatment is builtin in the same unit.
The sewage treatment unit product consists of biological and physical/chemical based treatment. The sewage treatment units are designed to work together with the vacuum collecting units
Vacuum piping components such as vacuum interface valves, non-return valves, air valves and chemical dosing units.
Grey water collecting units/pump stations
For galley and kitchen waters there is available an integrated grey water collecting unit and a grease separator which saves space and simplifies the system.
Grease separators
Galley and kitchen water contain grease which is harmful for a piping system and a treatment process.
Operation
The toilet is flushed by pressing the push button. The pneumatic push button is connected to the control mechanism with a control hose. Which transports the air pulse from push button to the control mechanism. The air pulse starts the flushing sequence and the control mechanism connects the vacuum to the control connections of the watervalve and the dischargevalve. The water valve opens and lets rinsing water flow into the bowl through the flushing ring After a short delay, the vacuum acts in discharge valve housing and forces the rubber diaphragm in discharge valve to open. The contents of the bowl is drained to the vacuum sewer by a pressure difference between the bowl and vacuum sewer.
The flushing cycle in the control mechanism starts the closing cycle. Atmospheric air pulse enters the discharge valve, which closes. After a short delay, atmospheric air pulse reaches watervalve, which closes and lets a certain level of water at the bottom in the bowl. After the flushing cycle has stopped, the push button and system will be ready for next flush.
The toilet is flushed by pressing the push button. The pneumatic push button is connected to the control mechanism with a control hose. Which transports the air pulse from push button to the control mechanism. The air pulse starts the flushing sequence and the control mechanism connects the vacuum to the control connections of the watervalve and the dischargevalve. The water valve opens and lets rinsing water flow into the bowl through the flushing ring After a short delay, the vacuum acts in discharge valve housing and forces the rubber diaphragm in discharge valve to open. The contents of the bowl is drained to the vacuum sewer by a pressure difference between the bowl and vacuum sewer.
The flushing cycle in the control mechanism starts the closing cycle. Atmospheric air pulse enters the discharge valve, which closes. After a short delay, atmospheric air pulse reaches watervalve, which closes and lets a certain level of water at the bottom in the bowl. After the flushing cycle has stopped, the push button and system will be ready for next flush.
(ii) State the advantages of Vacuum Sewage System.
One
of the main advantage of this system is that, very little flushing
water is required and the volume of sewage dealt with can be much
reduced with the downsizing of relevant equipment and cost saving. This
has made them very popular for passenger vessels. Lloyd’s regulations
state that the capacity of a sewage system for flushing water with
conventional plant is 115 liters/ person/ day and 15 liters for vacuum
systems.
Other advantages
- No deposits in the toilet, reduced use of detergents
- Very hygienic
- Flexible and convenient
- No deposits in the pipes
- Odour-free
- Facilitates reuse of urine and faeces
(iii) State the different causes of dropping vacuum.
Trouble :- The ejector pumps do not create enough vacuum.
Possible cause :- Sewage plug in the ejector.
Remedy :-
a) Make sure that pump is stopped and shut-off valve is closed
b) Remove plug and clean out ejector If this procedure is unsuccessful, the
following steps should be taken
c) Dismantle flange connections and remove bend.
d) Dismantle flange connections and remove ejector from tank
e) Dismantle flange connections and remove connection cone.
Withdraw non-return valve from ejector.
g) Clean sealing surfaces and if necessary replace rubber flap.
h) While the ejector is dismantled, it is advisable to check the nozzle and the
inside of the ejector housing for sludge and impurities
i) Refit ejector and non-return valve in reverse order lo dismantling, at same time
checking the condition of all seals and replacing as necessary.
Make sure that non return valve is correctly positioned.
Possible cause :- Sewage plug in the ejector.
Remedy :-
a) Make sure that pump is stopped and shut-off valve is closed
b) Remove plug and clean out ejector If this procedure is unsuccessful, the
following steps should be taken
c) Dismantle flange connections and remove bend.
d) Dismantle flange connections and remove ejector from tank
e) Dismantle flange connections and remove connection cone.
Withdraw non-return valve from ejector.
g) Clean sealing surfaces and if necessary replace rubber flap.
h) While the ejector is dismantled, it is advisable to check the nozzle and the
inside of the ejector housing for sludge and impurities
i) Refit ejector and non-return valve in reverse order lo dismantling, at same time
checking the condition of all seals and replacing as necessary.
Make sure that non return valve is correctly positioned.
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