Publicidad
Idiomas disponibles
Idiomas disponibles
Blowdown valve for bleeding dirt
and sludge for steam boilers
Model 660/660A
1 - Assembly
Before installing the valve, the following points should be noted:
• Installation may be in horizontal or vertical position.
• Pay attention to installation position. The manual lever must be able to move freely.
• Pay attention to flow direction. The arrow indicating flow direction is marked on the body of the valve.
• Remove plastic plugs, if provided. The plastic plugs are only for use during transport.
• Clean the sealing surfaces on both flanges.
Note:
To avoid water impacts, the piping behind the blowdown valve should be laid with a slope or the piping must be emptied before the
blowdown process.
2 - Start-up
The flange connections must be screwed tightly and must be leaktight.
Foreign bodies, corrosion products or welding residues from new systems can block the blowdown pipe in front of the blowdown valve or
the valve itself in a very short time. To avoid this, the boiler must be filled up to the level of the boiler rating plate with water. After this, the
boiler should be emptied again.
Important: During the emptying process, the quick shut-off blowdown valve is to be replaced by a flange adapter or by another suitable
valve. The boiler should then be filled again.
While the boiler is being heated up from the cold state, the blowdown valve should be operated fully several times, at least every 15
minutes. The blowdown valve must close so that it is leaktight automatically.
We recommend that the intervals between blowdown procedures is shortened initially for use in unrinsed new systems.
3 - Operation
Warning!
The valve is under pressure during operation.If flange connections, screw plugs or packing glands are loosened, hot water or
steam will flow out.The valve is hot during operation, and can cause severe burns.
Danger of crushing due to movable inner parts can cause serious injury during operation. Do not touch the quick shut-off blowdown valve
when activating it. Automatically controlled quick shut-off blowdown valves are time-controlled and can open and close abruptly.
3.1 - Determining the pulse/break times
To determine the blowdown pulse duration and the blowdown break time, in the first stage the entire amount of boiler water to be drained
(consisting of drainage quantity) is to be determined via the desalting and blowdown process. For a rough estimate, please check the
instructions noted on the leaflet:
Efficiency and Emptying
Where:
Bleeding processes should coincide as far as possible with moments when
R = Real steam production of the boiler. (kg/h)
the water is at rest or at minimum steam extraction, so that the deposits are
A = Water supply (l/h)
collected at the bottom of the boiler.
P = Water extracted in the bleeding process (l/h)
S = Water supply conductivity (µS/cm)
Carry out bleeding process at least every 8 hours. The effective duration
C = Desired conductivity inside the boiler (µS/cm)
is estimated to be 3 ÷ 4 seconds although we recommend you keep to the
Amount of water extracted in the bleeding process:
following mathematical model:
To establish the salinity of the water, the quantity of salts extracted per unit
of time must be equal to that of the water supply in this same period. Which
can be expressed:
S
A = C
P
•
•
Water supply conductivity [µS/cm] · Water supply [l/h] =
Desired conductivity inside the boiler [µS/cm] · Water extracted in the bleeding process [l/h]
See operating instructions B002 Water characteristics.
It is recommended that approximately 5% of the amount of drainage water to be discharged via the quick-acting sludge drain valve.
For the duration of a flush pulse, i.e. the interval during which the valve is completely open, we recommend that you stick to the
indicative value of approximately 2 seconds. The optimum sludge purge effect is achieved with short pulses.
The pause interval of the sludge purge, i.e. the time during which the valve is closed, should be determined according to the size and
output of the steam generator, the boiler water quality, the operating load, the percentage of condensate and the hard water quality. This
interval can be in the range from 0.1 hours to 10 hours or more.
Example:
For the DN the volume (q) in l/s can be calculated as shown in the
diagram.
The quotient (P/q) tells us the intervals between bleeding
processes and the duration of them (T) in seconds per hour.
Example:
Amount of water extracted in the
bleeding process
(P) = 80 l/h
Boiler pressure
(p) = 3 bar
Volume
(q) = 8 l/s
Note:
If the boiler does not have a desalting device, or if the necessary quantity of water cannot be discharged from the boiler with the existing
desalting device, the break times between the blowdown procedures should be reduced. Only when no further reduction is possible can
the pulse time be increased; the pulse time should not exceed 5 seconds.
3.2 - Operation using manual blowdown valve
The largest sludge removal will be achieved after a standard switching off of the boiler, when the suspended matter in the boiler has settled
on the base of the boiler. In the blowdown procedure, the manual lever should be pressed quickly down as far as it will go for two seconds.
The boiler should preferably be at operating pressure.
Pressing the manual lever slowly or for too long will not remove the sludge as required.
After operation, return the manual lever to its position quickly, but do not let it spring back on its own. If it's done repeatedly, this can
damage the quick shut-off blowdown valve.
If the blowdown valve does not close tightly, the manual lever should be operated briefly, as described.
3.3 - Operation and emergency operation of automatic blowdown valve
The pulse/break times determined are set in the automatic blowdown device (MP-2). This means that no further operation is necessary.
4 - Shutting down
Can cause serious burns and scalds all over the body. Before flange connections, packing gland joints or screw plugs are loosened, all
the connected pipes must be unpressurised (0 bar) and at room temperature (20°C).
5 - Measures in the event of unusual observations and operating faults
If anything unusual is observed and/or operating faults are displayed, the following table provides initial information on repair.
Observation/fault: Water leaking out at inspection bore
Cause: Damaged seal
Repair: Change seal
Observation/fault: Boiler water is foaming
Cause: Blowdown volume too low
Repair: Reduce blowdown break time
Observation/fault: Boiler showing lack of water
Example:
Cause: Blowdown volume too high
R = 1520 kg/h
R
S
•
Repair: Increase blowdown break time
P =
S = 200 µS/cm
C - S
C = 4000 µS/cm
P = 80 l/h
6 - Care and Maintenance
Manipulation of the valve while working can cause serious burns and scalds all over the body. Before the following or any other maintenance
work is carried out on the valve, or flange connections, packing gland joints or screw plugs are loosened, all the connected pipes must be
unpressurised (0 bar) and at room temperature (20°C).
Blowdown valves are basically maintenance-free.
After every boiler cold start, the blowdown valve should be operated once after the mean working gauge pressure has been reached. The
valve must close tightly automatically.
The packing gland must be leak-tight. In this connection, the inspection bore should be inspected for leakage of the medium.
Operate blowdown valve once; the blowdown valve must close tightly automatically.
T = 10s.
The boiler will bleed itself for 10 seconds every hour
If the bleeding time is of 3 seconds = 3 bleeding every
hour
The interval between bleeding should be of 20 minutes.
Boiler pressure in bar
6.1 - Replacing the membrane of the automatically operated blowdown valve
- Remove pressure pipe for the control of the membrane drive.
- Loosen and remove hexagon bolts and hexagon nuts.
- Remove and clean upper part of the membrane drive.
- Remove old control membrane. Clean lower part.
- Insert new control membrane and position on the perforated circle of the lower part.
- Put on upper part and position on perforated circle.
- Insert hexagon bolts, screw on with hexagon nuts and tighten.
- Mount pressure pipe for the control of the membrane drive.
- Test for leak-tightness, if necessary carefully tighten hexagon bolts.
Note:
Do not apply more than 5 Nm to tighten the control membrane. Any further tightening torque could damage the control membrane.
6.2 - Conversion from manual to automatic blowdown valve
A manual quick shut-off blowdown valve can be automated by retrofitting with a membrane drive.
It's recommended sending to the factory to carry out the conversion operation.
6.2.1 - Lever/pedal assembly
Lever DN-20 and 25
Pedal DN-32, 40 and 50
1
2
Assembly
Vertical assembly
Horizontal assembly
Assembly
7. Spare parts
To order or consult prices of spare parts, please contact the commercial department of VYC Industrial.
Informative brochure, without obligation and subject to our General Sales Conditions.
Founded in 1914
www.vycindustrial.com
Avenc del Daví, 22
Pol. Ind. Can Petit
08227 TERRASSA (Barcelona) SPAIN
+34 93 735 76 90
119
info@vycindustrial.com
3.1
4.1
3.2
4.2
Vertical assembly
Horizontal assembly
Publicidad
