PRESSCON HORTI User manual

User manual
Safety valves (Vacuum-overpressure safety valve and vacuum safety
valve)
Type
:
Manual safety valve
Datum
:
07-04-2021
Version / Revision
:
Version 3.0 Revision00
Status
:
Accepted
Company
:
PRESSCON
Location
:
Honselersdijk

Page 2 of 18

Page 3 of 18
Table of contents
Introduction........................................................................................................................................................ 4
1. Precautions and safety instructions........................................................................................................... 4
2. Application ................................................................................................................................................. 5
3. Construction............................................................................................................................................... 6
3.1 Vacuum-overpressure safety valve ................................................................................................... 6
3.2 Vacuum safety valve.......................................................................................................................... 7
4. Functioning of the safety valves ................................................................................................................ 8
4.1 Operation of a vacuum-overpressure safety valve............................................................................ 8
4.2 Operation of a vacuum safety valve .................................................................................................. 8
5. Construction............................................................................................................................................... 8
6. Mounting.................................................................................................................................................... 9
7. Test.......................................................................................................................................................... 10
8. Maintenance ............................................................................................................................................ 10
8.1 Maintenance for vacuum-overpressure safety valves..................................................................... 10
8.1.1 Annual check-up of the vacuum-overpressure safety valve........................................................ 10
8.1.2 Criteria for the replacing of the vacuum and overpressure pallets.............................................. 11
8.1.3 Methods for the revision of the vacuum-overpressure safety valve............................................ 12
8.2 Maintenance for vacuum safety valves ........................................................................................... 13
8.2.1 Annual check-up of the vacuum safety valve .............................................................................. 13
8.2.2 Revision of the vacuum safety valve ........................................................................................... 13
9. Technical data ......................................................................................................................................... 14
9.1 Technical data vacuum-overpressure safety valves ........................................................................... 14
9.1.1 Technical data PV 200/25/20-2 ................................................................................................... 14
9.1.2 Technical data PV 150/25/20-2 ................................................................................................... 14
9.1.3 Technical data PV 80/25/20-2 ..................................................................................................... 14
9.2 Technical data vacuum safety valves.............................................................................................. 15
9.2.1 Technical data PV100-2-F........................................................................................................... 15
9.2.2 Technical data PV80-2-F............................................................................................................. 15
9.2.3 Technical data PV50-2-F............................................................................................................. 15
10. Warranty .............................................................................................................................................. 16
11. Appendix.............................................................................................................................................. 17
12. Document history................................................................................................................................. 17
13. To Conclude ........................................................................................................................................ 18

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Introduction
Before anything else, we’d like to congratulate you with the purchase of a PRESSCON vacuum-
overpressure safety valve or a vacuum safety valve. The vacuum-overpressure safety valve and vacuum
safety valve will provide safety against overpressure and a vacuum for your buffer tank. To clarify the usage
and functioning of your vacuum-overpressure safety valve and vacuum safety valve we offer you this
manual.
1. Precautions and safety instructions
During working with the vacuum-overpressure safety valve and the vacuum safety valve there are several
safety hazards that need to be taken into account. These are important both while working and installing the
safety valves. We highly recommend taking these safety hazards into account before proceeding to work
with the vacuum-overpressure safety valve and the vacuum safety valve.
Symbol
Description
Applies to
WORKING WITH HEIGHTS,
Vacuum-overpressure safety valves and vacuum safety
valves that are mounted on a vertical or horizontal buffer
tank are usually placed a couple of metres from the
ground. In most cases while working on the safety
valves, the height exceeds 2,5 metres. This is why
working on the safety valves is considered working with
heights. It automatically means that a safety harness or
other adequate fall protection is mandatory.
-Vacuum-overpressure safety
valve on a vertical buffer tank;
-Vacuum safety valve on a
horizontal buffer tank.
HOT PARTS AND STEAM,
The nitrogen above the water in the vertical buffer tank
has a humidity of 100% and is able to reach a
temperature of 90°C. So the housing of a safety valve
and the steam that is released can be hot. During
disassembling a safety valve or the safety pallets there
is an increased risk of injury caused by combustion.
Take appropriate measures for this. Use fitting safety
apparel and consider for example the direction of the
wind.
-Housing of the vacuum-
overpressure safety valve on a
vertical buffer tank;
-The releasing of nitrogen by the
vacuum-overpressure safety
valve;
-Housing of the vacuum safety
valve on a horizontal buffer
tank.
ADDITIONAL EXPOSURE TO HOT STEAM,
In some cases the safety valve as an extra cover of
insulation material. Keep in mind that this enables the
hot steam to rise higher when the nitrogen is being
released.
-The releasing of nitrogen by the
vacuum-overpressure safety
valve which is covered with
additional insulation material.

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2. Application
Application vacuum-overpressure safety valve
The application of the PRESSCON vacuum-overpressure safety valve is the following:
The vacuum-overpressure safety valve is placed near the caged ladder on 0,5 m. out the cylindrical side of
the vertical buffer tank on the roof. The vacuum-overpressure safety valve then provides the vertical buffer
tank with protection against vacuum and overpressure.
Application vacuum safety valve
The application of the PRESSCON vacuum safety valve is the following:
Two vertical pieces of tube with welding flanges are welded on the two highest ends of a horizontal buffer
tank. The tubes have a diameter of 2” . On each of the flanges a PRESSCON vacuum safety valve is
mounted. The vacuum safety valve provides protection for the horizontal buffer tank against vacuum.

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3. Construction
3.1Vacuum-overpressure safety valve
The image below is a schematically drawn image of the vacuum-overpressure safety valve.
1. Overpressure valve
2. Overpressure lead
3. Overpressure pallet
4. Operating pressure valve
5. Operating pressure lead
6. Operating pressure pallet
7. Cover plate
8. Silicon gasket
9. Vacuum pallet
10. Safety valve housing
1.
2.
3.
10.
9.
8.
7.
6.
5.
4.
Figure 1. Vacuum-overpressure safety valve

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3.2Vacuum safety valve
The image below is a schematically drawn image of the construction of a vacuum safety valve.
1. Cover plate
2. Vacuum pallet
3. Gasket
4. Safety valve housing
5. Gasket
6. Adjustment bolt
7. Vacuum pallet flange
8. Gauze
9. Assembly
10. M8 RVS nut
11. M8 RVS ring
12. RVS stud bolt M6x10
1.
2.
3.
4.
5.
7.
8.
9.
10.
12.
11.
10.
11.
6.
Figure 2. Vacuum safety valve

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4. Functioning of the safety valves
4.1Operation of a vacuum-overpressure safety valve
If the pressure of the nitrogen above the water rises above the maximum operating pressure for any reason,
the operating pressure side of the vacuum pressure relief valve opens. This creates an open connection to
the outside air. The excess nitrogen can flow away through the opening. The working pressure valve
remains open until the pressure equals the operating pressure.
If the pressure keeps rising and reaches the maximum overpressure, the overpressure safety valve will also
open. The vacuum relief valve remains open until the pressure falls below the maximum overpressure.
When the pressure drops and a vacuum is created between -2 and -4 mbar, the vacuum relief valve on the
vacuum side opens. Due to the pressure difference between the outside and inside air, outside air flows in.
The pallet is lifted until the pressure difference is equalised.
By using a PRESSCON vacuum-overpressure safety valve the possibility of an unacceptable over- or under
pressure altering the lasting shape of the tank is prevented. To guarantee a correct operation of the vacuum-
overpressure safety valve it is prohibited to change the lead weights in the safety valve in any way.
4.2Operation of a vacuum safety valve
If water flows from the buffer tank and causes a decrease in the water level, then the water level will
foremost decrease in the vacuum safety valve. If the water in the housing of the vacuum safety valve drops
more, a vacuum will be created. When a vacuum exists between -2 and -2 mbar, the pallet of the seating will
be lifted. This causes an open connection with the outside air. Because of the differential pressure between
outside and inside, outside air will flow into the buffer tank. The differential pressure is settled. By applying a
PRESSCON vacuum-overpressure safety valve the possibility of an unacceptable over- or under pressure
altering the lasting shape of the tank is prevented. To guarantee a correct operation of the vacuum safety
valve it is absolutely prohibited to turn the adjusting screw on the downside of the valve. The adjusting screw
is adjusted and secured in the factory.
5. Construction
PRESSCON has aimed to make the construction of the vacuum-overpressure safety valve as simple as
possible. Except for the flange for the mounting on the tank, only the gasket under the pallets is capable of
leaking. A very durable rubber is chosen as the material for the gasket. As a seal between the inside and the
outside, a combination of a stainless steel seating with a special rubber has been chosen. An important
feature of this special rubber is its lack of permit for dirt to attach itself to the rubber. The rubber is also very
heat resistant. The vacuum-overpressure and vacuum safety valve are constructed in such a way that after
assembly they are completely resistant to a plurality of pressures that can occur at a vertical or horizontal
buffer tank.

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6. Mounting
Mounting the vacuum-overpressure safety valve
The mounting of the vacuum-overpressure safety valve is as follows:
Make sure there are no irregularities on the flange of the vacuum-overpressure safety valve other than the
placed components of the manufacturer. Loosen all the RVS nuts on the threaded ends. Place a rubber
gasket of the correct dimensions on de welding flange. Place the vacuum-overpressure safety valve on the
flange with the threaded ends through the holes in the welded flange. Tighten the nuts on the threaded ends.
Make sure that all the nuts are all tightened even. Make sure that the connection between the welded flange
and the valve is leak-proof. The valve is now company ready.
Mounting the vacuum safety valve
The mounting of the vacuum safety valve is as follows:
Make sure there are no irregularities on the flange of the vacuum safety valve other than the placed
components of the manufacturer. Place a rubber gasket on the welded flange. Place the vacuum safety
valve on the four holes on the welded flange. Place 4 M16 bolts through the holes and place 4 M16 nuts on
the bottom side. Make sure all the nuts are tightened even. Make sure that the connection between the
welded flange and the valve is leak-proof. The valve is now company ready.

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7. Test
Each PRESSCON produced vacuum-overpressure safety valve and vacuum safety valve is adjusted and
tested according to the regulations. Every vacuum-overpressure safety valve or vacuum safety valve is
provided with a unique serial number. The serial number is also mentioned on the test certificate. The test
certificate is added to the manual.
8. Maintenance
Every vacuum-overpressure safety valve and vacuum safety valve has to be checked yearly to guarantee a
correct operation. It is advised to let the vacuum-overpressure safety valve and the vacuum safety valve be
checked once a year and revised once every two years. The vacuum-overpressure safety valve can be
revised on the site by a mechanic of PRESSCON or an instructed technician. The vacuum safety valve can
only be revised in the factory of PRESSCON. There is an exchange program available with revised vacuum
safety valves in stock.
8.1Maintenance for vacuum-overpressure safety valves
8.1.1 Annual check-up of the vacuum-overpressure safety valve
To check if the vacuum-overpressure safety valve is working satisfactorily, the annual inspection should be
performed according to the following work instruction.
1. Start by checking the pressure of the nitrogen blanket. This can be seen on the display of the
nitrogen generator.
2. Then climb the buffer tank and check whether the safety device is blowing or not. The type plate of
the safety valve indicates the operating pressure and the maximum pressure. Decide on the basis of
this information if the safety valve should be blowing off or if this should be closed.
Caution! When opening the vacuum overpressure safety device, steam is released with
a temperature of 90°C. It is recommended to wear protective gloves and additional
protective clothing.
2.
1.
3.
Figure 3. Vacuum-overpressure safety valve

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3. Make sure the pallets (valves) of the safety valve don’t clamp. If the pallets are shortly lifted by hand,
they should seal off immediately and should not linger. The safety valve and the pallets can be very
hot, so it might be convenient to use a tool to lift the pallets up.
4. Are the silicon rings of the pallets in order? Disassembly the safety valve according to 8.1.3
‘Methods for the revision of the vacuum-overpressure safety valve.’ and inspect the silicon rings on
irregularities and their suppleness.
8.1.2 Criteria for the replacing of the vacuum and overpressure pallets.
During the check-up of the vacuum and overpressure pallets the following criteria have to be taken into
account. These determine if the pallets have to be replaced or not. The pallets have to be replaced if:
1. One of the pallets doesn’t seal off correctly automatically. The pallets are always replaced in a set.
So the overpressure pallet, operating pressure pallet and vacuum pallet need to be renewed as a
set.
2. It is contractually agreed upon that the vacuum and overpressure pallets will undergo a preventive
renewal every two years. This has to be mentioned in the maintenance contract of the PRESSCON
expansion system.
Example: This safety valve as the pressure of ‘’25-20-2’’, which means:
De smallest valve opens at 20 mbar (Operating pressure) (Figure 3 no. 1)
The big valve opens at 25 mbar (Maximum pressure) (Figure 3 no. 2)
The vacuum valve opens at -2 mbar (Vacuum) (Figure 3 no. 3)
If the pressure is lower than 20 mbar the safety valve should be closed;
If the pressure is higher than 20 mbar the smallest valve should be open;
If the pressure is higher than 25 mbar the big valve should be open too.
De smallest valve opens at 20 mbar (Operating pressure) (Figure 3 no. 1)
The big valve opens at 25 mbar (Maximum pressure) (Figure 3 no. 2)
The vacuum valve opens at -2 mbar (Vacuum) (Figure 3 no. 3)
If the pressure is lower than 20 mbar the safety valve should be closed;
If the pressure is higher than 20 mbar the smallest valve should be open;
If the pressure is higher than 25 mbar the big valve should be open too.

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8.1.3 Methods for the revision of the vacuum-overpressure safety valve.
The vacuum-overpressure safety valve that is mounted on a vertical buffer tank can be revised on the spot
according to the following work instructions. These do not apply to the vacuum safety valves on a horizontal
buffer tank. For the revision of the vacuum-overpressure safety valve the pallets must be replaced. Proceed
as follows:
1. Disassembly both lids (Figure 4 no. 1) of the safety valve by loosening the wing nuts on the top.
2. Depressurise the buffer tank by tilting one of the overpressure pallets (Figure 4 no. 2). This way, the
nitrogen can escape from the tank. Beware of the steam that forms by doing this! The pressure
of the nitrogen blanket now turns to 0 mbar. This generates a ‘Pressure Minimal’ alarm on the
nitrogen generator.
3. Remove both pallets (Figure 4 no. 2) when all steam has been blown off.
4. Disassembly the cover mounted on the housing of the safety valve. (Figure 4 no. 3). This can clamp
a bit because of the old gasket. The cover needs to be pried off by hand because of the risk of
damage that would cause an inability to close off correctly.
5. Remove the old silicon gasket (Figure 4. no. 4) and renew the vacuum pallet (Figure 4. no. 5).
6. Place a new silicon gasket (Figure 4. no. 4) on the housing of the safety valve and mount the cover
back on (Figure 4. no. 3). Tighten the nuts evenly.
7. Place new overpressure pallets (Figure 4. no. 2) and put the lead of the old pallets on the new
pallets.
8. Place the lids of the safety valve (Figure 4. no. 1) back and attach it with the wing nuts.
1.
2.
3.
5.
4.
Figure 4. Vacuum-overpressure safety valve

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8.2Maintenance for vacuum safety valves
8.2.1 Annual check-up of the vacuum safety valve
To check if the vacuum safety valve works satisfactorily, an annual visual inspection needs to be conducted.
The vacuum safety valve passes this visual inspection if the following criteria are met:
-The vacuum safety valve is free of leakage that would cause water to flow out of the buffer tank;
-The gaskets of the vacuum safety valve and between the safety valve and the welded flange look
undamaged and do not give rise to suspected water or air leakage.
8.2.2 Revision of the vacuum safety valve
PRESSCON advises to let the vacuum safety valve be revised every two years. The vacuum safety valve
can only be revised in the factory of PRESSCON. An exchange program with revised vacuum safety valves
in stock is accessible for this. The vacuum safety valve needs to be demounted of the horizontal buffer tank.
The disassembling of the old vacuum safety valve and the mounting of the revised vacuum safety valve
needs to be carried out by a licensed installer that will be able to safely relieve the pressure of the buffer tank
and vacuum safety valve.

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9. Technical data
9.1 Technical data vacuum-overpressure safety valves
9.1.1 Technical data PV 200/25/20-2
Material housing : RVS 304
Material M16 tread ends : RVS 304
Material nuts : RVS 304
Material cover : RVS 304
Material gasket : Special rubber
Material M8 tread ends : RVS 304
Material valve plate : RVS 304
Material valve seat : RVS 304
Material seal : Special rubber
Flange connection : DN 200 PN6 (ND6)
Treaded ends : 8 pieces M16, including nuts
Overpressure opening : 25 mbar(o) (1,025 bar absolute)
Operating pressure opening : 20 mbar(o) (1,020 bar Absolute)
Opening pressure vacuum : -2 tot –4 mbar(o)(0,998 –0,996 bar absolute)
Maximum temperature : 120 C
9.1.2 Technical data PV 150/25/20-2
Material housing : RVS 304
Material M16 tread ends : RVS 304
Material nuts : RVS 304
Material cover : RVS 304
Material gasket : Special rubber
Material M8 tread ends : RVS 304
Material valve plate : RVS 304
Material valve seat : RVS 304
Material seal : Special rubber
Flange connection : DN 150 PN6 (ND6)
Treaded ends : 8 pieces M16, including nuts
Overpressure opening : 25 mbar(o) (1,025 bar absolute)
Operating pressure opening : 20 mbar(o) (1,020 bar Absolute)
Opening pressure vacuum : -2 tot –4 mbar(o)(0,998 –0,996 bar absolute)
Maximum temperature : 120 C
9.1.3 Technical data PV 80/25/20-2
Material housing : RVS 304
Material M16 tread ends : RVS 304
Material nuts : RVS 304
Material cover : RVS 304
Material gasket : Special rubber
Material M8 tread ends : RVS 304
Material valve plate : RVS 304
Material valve seat : RVS 304
Material seal : Special rubber
Flange connection : DN 80 PN6 (ND6)
Treaded ends : 4 pieces M16, including nuts
Overpressure opening : 25 mbar(o) (1,025 bar absolute)
Operating pressure opening : 20 mbar(o) (1,020 bar Absolute)
Opening pressure vacuum : -2 tot –4 mbar(o)(0,998 –0,996 bar absolute)
Maximum temperature : 120 C

Page 15 of 18
9.2Technical data vacuum safety valves
9.2.1 Technical data PV100-2-F
Material housing : RVS 304
Material nuts : RVS 304
Material cover : RVS 304
Material gasket : Special rubber
Material M8 tread ends : RVS 304
Material valve plate : RVS 304
Material valve seat : RVS 304
Material seal : Special rubber
Flange connection : DN 100 PN6 (ND6)
Holes : 4 pieces, suitable for M16 bolts
Continues pressure : 1,5 bar(o) (2,5 abs.)
Maximum peak pressure : 3 bar(o) (4 abs.)
Opening pressure vacuum : -2 tot –4 mbar(o)(0,998 –0,996 bar absolute)
Maximum temperature : 120 C
9.2.2 Technical data PV80-2-F
Material housing : RVS 304
Material nuts : RVS 304
Material cover : RVS 304
Material gasket : Special rubber
Material M8 tread ends : RVS 304
Material valve plate : RVS 304
Material valve seat : RVS 304
Material seal : Special rubber
Flange connection : DN 80 PN6 (ND6)
Holes : 4 pieces, suitable for M16 bolts
Continues pressure : 1,5 bar(o) (2,5 abs.)
Maximum peak pressure : 3 bar(o) (4 abs.)
Opening pressure vacuum : -2 tot –4 mbar(o)(0,998 –0,996 bar absolute)
Maximum temperature : 120 C
9.2.3 Technical data PV50-2-F
Material housing : RVS 304
Material nuts : RVS 304
Material cover : RVS 304
Material gasket : Special rubber
Material M8 tread ends : RVS 304
Material valve plate : RVS 304
Material valve seat : RVS 304
Material seal : Special rubber
Flange connection : DN 50 PN 10/16
Holes : 4 pieces, suitable for M16 bolts
Continues pressure : 1,5 bar(o) (2,5 abs.)
Maximum peak pressure : 3 bar(o) (4 abs.)
Opening pressure vacuum : -2 tot –4 mbar(o)(0,998 –0,996 bar absolute)
Maximum temperature : 120 C

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10. Warranty
PRESSCON guarantees a warranty on the materials and the construction for 12 months after the selling
date. This under the condition that the placement of the vacuum-overpressure safety valve or vacuum safety
valve has been performed by expert and skilled personnel, in accordance with these mounting prescriptions.
The installation has to be provided with correctly, and according to the prescriptions, adjusted pressure
safety equipment at all times on the water side. The maximum temperature is set at 120C. The PRESSCON
vacuum-overpressure safety valves and vacuum safety valves that are applied at systems where there are
impurities in the water in the form of oil and in the case of oil residue and the like in the buffer tank, and in
this way are able to hinder the operation of the valves, are excluded from the warranty. It should always be
ensured that the installation, including the vacuum-overpressure safety valve or vacuum safety valve, is not
able to freeze.

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11. Appendix
In addition to this document, the description of the content extends to the following appendixes:
Appendix ID
Description
Version
-
-
V0.0_R00
12. Document history
Version 1.0 to 2.0 indicates : Modification, in lay-out, structure or other major modifications;
Version 1.0 to 1.1 indicates : Supplement, a chapter of paragraph has been added to the document;
Revision _R01 to _R02 indicates : Correction, an image, language error or text error has been corrected.
Version
Date
Modification
1.0_R01
15-01-2016
First concept release
19-01-2016
Chapter 8.1.1. text under example, grammar corrected;
Chapter 8.2.1. 2nd line, grammar corrected.
2.0_R00
22-03-2021
Minor textual changes.
Safety warning added 8.1.1
3.0_R00
07-04-2021
New layout

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13. To Conclude
This manual has been written in order to support the mechanic, installer or customer in adjusting, modifying
or working with a product of PRESSCON. Its aim is to maintain and possibly improve the quality of its
products. If additional information or support is requested then PRESSCON can be consulted through the
following information.
Veilingweg 27 A
2675 BR
Honselersdijk
Tel:
Web:
E-mail:
[phone]
www.presscon.nl
[email protected]