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SSV 18 Automatic Recirculation Valvewith standard bypass valve head
SSV 18 Automatic Recirculation Valve withstandard bypass valve head andadditional branch DN4 (see para 8)
SSV 20 Automatic Recirculation Valve withenlarged bypass valve head for high
minimum flow rates
SSV 20 Automatic Recirculation Valve withenlarged bypass valve head for highminimum flow rates and additional branchDN 4 (see para 8)
1. General description/Applications/Mode of Operation Page 22. Guarantee Page 33. Safety Page 34. CE-Conformity, design according to AD-regulation Page 35. Marking of the valve Page 46. Valve specifications Page 47. Start-Up-Trim Page 58. Additional branch (optional) Page 59. Protection during transport and storage Page 5
10. Installation instructions Page 6
11. Start-up Page 612. Maintenance and repair Page 713. Recommendation for checking of parts subject to normal wear Page 714. Disassembly of the Bypass unit Page 815. Assembly of the Bypass unit Page 916. Disassembly of the Valve Page 917. Assembly of the Valve Page 1018. Remarks regarding drawing and parts list Page 1019. Manufacturer Page 10
1. General description / Applications / Mode of Operation
a) Applications
The Automatic Recirculation Valve is a protection device. It automatically protects centrifugalpumps, especially hot water pumps, from damage which might occur through partial evaporation of
the pump content during low load operation.As soon as the main flow falls below a predetermined rate, the valve opens it's bypass sufficientlyto maintain the required pump minimum flow rate, even if the main flow is zero.
The Valve range SSV18/20 is applied in cases where a non-return valve in the bypass-branchis required.
b) Mode of Operation
The non-return cone pos. 3 of the Automatic Recirculation Valve is kept at a determined levelby the main flow. The cone only responds to the flow in main direction and not to the pressure.The valve is designed in such a way that the cone reaches final position at denominated main flow
latest. The non-return cone activates the Rotary Slide Valve (Pos. 13) in the bypass branch by meansof a lever. If the cone is positioned on the seat, the Rotary Slide Valve is completely open.The requiredminimum flow of the pump Qby resp. Qmin is delivered via the bypass. The cone rises with increasingmain flow thus closing the bypass more and more (modulating bypass control).The branching ends as soon as the main flow exceeds the pump minimum flow. The bypass isclosed. Vice versa the bypass opens again as soon as the main flow falls below the requiredminimum flow.The data indicated on the name plate under para 5 "Marking of the Valve" have been taken as abasis for correct function of this application. If different operating data are applied, increased wear ofthe installed parts can be expected, depending on the degree of deviation. On principle we recommendto consult us in case of altered operating data, so that the valve can be modified accordingly.
Illustration 1Bild 1 Return of the bypass flow for
The valve has been produced based on the operating data as per para 5 and 6. It is only applicable forthese data. If you intend to use the valve for other operating conditions, a technical review is imperative
with a subsequent release note from Schroeder Valves GmbH & Co. KG and the orderer.If the valve is applied for other conditions without our agreement, any guarantee claims expire.Any repairs or modifications during the guarantee period may only be executed by our speciallytrained personnel or with our written approval.
3. Safety
3.1 The operator is responsible for the observation of the security regulations at site.3.2 The assembly personnel must be sufficiently qualified and trained.
The connecting flanges are designed without consideration of external flange forces. The pipes areto be connected in such a way, that no tension occurs.The structural weight of the valve has been designed for water filling. Other external loads are notadmissible. Loads which might occur through traffic, wind or earthquakes have not been considered.Before assembly/dismantling of the valve the plant has to be at zero pressure. The temperature ofthe surfaces and medium must be lowered to room temperature.The valve is supplied without insulation and protection against contact. If there is a considerabledifference between operating and room temperature, an insulation resp. Protection against contacthas to be provided from the operator before start-up.If the valve operates with dangerous fluids, a visible warning sign has to be provided close by thevalve.For the assembly suitable and tested lifting equipments are to be used, depending on the valveweight (please also see para 10 "Installation Instructions")
3.9 Suitable facilities for draining and de-aeration are to be provided near the valve in the piping.3.10 During dismantling a residue of the medium still may be found above the cone. If the medium is
dangerous, appropriate security measures have to be taken.
3.11 The operator has to provide security equipment like relief valves or similar, pressure gauges anddevices for temperature supervision.3.12 The valve is designed for a continuous operation with static pressure load. An operation of the
valve with frequently increasing or changing loads is not to be expected and has not been takeninto account.
3.13 The function of the valve can be affected by pollution and solids. Therefore we recommend to filterthe medium with a max. width of mesh of <150 µm before it enters the valve.
3.14 The valve has to be inspected regularly according to local and legal safety regulations. Especiallythe pressure bearing parts and connecting parts are to be checked for wear and corrosion.
3.15 Spare parts are to be used according to the parts listed related to the order. They are to beobtained exclusively from our company.
3.16 It is not admitted to utilize the valve for any other application than the one it was designed for.A speed deviation of the pump of more than + 4% is not admissible.
4. CE - Conformity
The valve is admitted as pressure vessel according to the Pressure Equipment Directive 97/23 EG andreleased for sale within the European market. It has the following CE-marking:
Appertaining Certificates
EC-Design-Examination No. .........................................................................QA-System acc. to PED 97/23/EC - Certifikate-No.: ........................................
The calculation of the valve and the selection of the materials has been as per AD2000-regulations.
The Automatic Recirculation Valve has a name plate with all relevant valve data. Followingillustration shows the name plate of the first valve of the lot size . If there are more than one valve supplied,the manuf.-No varies accordingly.
Certified acc. to
EN ISO 9001
Automatic Recirculation Valve
l
Manuf.-No. Weight kg
Design Press. Year of Manuf. m³/h
Design Temp. °C m³/h
Test Press. bar
Made in Germany
The name plate is of aluminium and fastened with 4 notch nails at the lower casing. Additionally a hardstamp of the manuf. No is behind the name plate to make it possible to identify the valve in case of lossof the name plate.It is imperative to tell us the Manuf. No when ordering spare parts.
Additionally the flanges of the valves are stamped with material data (material, charge-no., sample no.)and the branch name with nominal diameter indication.
name plate
Illustration 2
6. Valve Specifications (additionally to name plate)
Flanges:
Inlet DN1
Outlet DN2
Bypass DN3
Sealing: Connection upper/lower casing with O-Ring Pos.78.1lower casing/ bypass-branch with O-Ring Pos.78.2
If the minimum flow is delivered via the bypass for longer periods of time during start-up, the technicallyhigh valued pilot elements Pos. 12 + 13 can suffer an increased wear. To avoid this, a so called Start-Up-Trim can be installed in the Start-Up period, which can deliver a constant bypass flow independently from
the main flow. The modulating bypass control as described under para 1.b) ist not given.
After the end of the start-up period the Start-Up-Trim is to be exchanged against the controlling partsPos. 12+13. For later change of the controlling parts we recommend, to consider a pipe part for removalbefore the bypass branch in construction. If the Start-Up-Trim has already been ordered with the valveorder, the Start-Up-Trim will be installed as standard fitting and the following illustrated plate is at thebypass branch. This has to be removed after the Start-Up periodand the exchange of the controlling partsas described before. (see para 14. -Disassembly of the Bypass unit))
By use of the Start-Up-Trim considerably longer duration of the technically high value controlling partscan be taken into account.
8. Additional branch (optional)
For following applications additional branches at the valve can be applied:
a) Hand operating branch
The hand operating branch with multi-stage throttle is fitted at the casing below the cone seat and servesto pass off the minimum flow via a hand-operated valve combination. We recommend the branch forprotection of the internal bypass parts at extreme operating conditions, e.g. at high differential pressuresand frequent operation in the range of the bypass flow as well as for filling and start up of the plant.The installation of the branch can be above or below the cone seat.
b) Warm-up branch
The warm-up branch is for warming/cooling of aggregates in pipe line systems. It can be suppliedwith or without throttle in the branch.
c) Drainage branch
The drainage fitting is for draining the pipe line above the cone seat. It is supplied without throttle.
d) Pressure gauge branch
The pressure gauge branch can be used for pressure and temperature measuring. The branch isfitted below the cone seat.
9. Protection during transport and storage
The Automatic Recirculation Valve is supplied unpacked, if not stated otherwise in the order. Theflanges are closed with plastic caps and steel bands. The valve is protected against corrosion in a drycondition with a means for conservation. This conservation is sufficient for indoor and ventilated storage
of up to 6 months. A longer storage requires an appropriate packing and should be indicated with theorder.
The installation position of the Automatic Recirculation Valve for the order isWe recommend to provide a straight pipe piece in the bypass line for maintenance, installation of partssubject to normal wear and for prevention of cavitation. This piece should have the same nominal diameter
as DN3 and a length of 5 x DN3. An increase or decrease of diameter, if required, should only be doneafter a minimum of 2-3 meters pipe line (see sketches). The workmanship of the bypass - piping mustconsider, that the piping behind the Bypass branch always must be filled to capacity. Otherwise thebypass parts are subject to a considerably wear. Vibrations are possible.
Illustration 3
Falsch!
The mounting of the Automatic Recirculation Valve has to be done such that the connected linesafter loosening of the screws do not cushion or gap or are attached together by pressure. Wheninstallation is horizontal the bypass should only show vertically upwards resp. Sidewards, so that noforeign particles can collect. The bypass line behind the branch must always be filled with medium.For the control and the installation of new parts it must be possible to draw the minimum flow linesidewards around the flange diameter. If this should not be possible with greater dimensions, a removablepipe piece is to be provided. The same is recommended after the outlet branch DN2 for easier assemblyand disassembly of the valve.The screws for the piping are to be applied according to the valid standards. The valve screws deliverd byus with the valve have a defined quality. If it is necessary to replace these screws, please pay attentionto the indicated material in the parts list.
11. Start-Up
The Start-Up of the Automatic Recirculation Valve is done together with the pump. During Start-Upagainst the closed gate valve in the main line a predetermined quantity, the bypass-flow, must flow via thebypass line. The correct opening and closing of the bypass should not only be controlled at the Start-Upbut also later regularly. (Flow noise can be heard, eventually use of a listening stick.)Note: Start-Up against closed gate valve slide is not only recommended in the beginning, but also duringnormal operation, as otherwise the bypass parts are subject to a considerably wear.In order to not fall below the bypass flow the closing resp. opening point of the bypass is designedmin. 17 % above the required bypass flow. Extended operation of the plant in the range of the closing-and opening points (75% - 140% of the bypass flow in main direction) result in increased wear, thisis to be observed especially during test operation.
Remarks for additional branch for hand-operated operation:
The additional branch with welded multistage throttle is fitted under the cone seat. The design is identicalwith the automatic bypass.Application: Especially during Start-up for protection of the automatic bypass. If the bypass flow isdelivered via the hand-operated branch, the automatic bypass is to be closed by a gate valve in the bypassline. Other functions are possible.
NOTE! Before normal operation of the Automatic Recirculation Valve the gate valve has to
be opened again in the bypass line. Otherwise pump damages can occur.
The Automatic Recirculation Valve is to be reviewed according to para 13.Foreign parts e.g. weld pearls etc. can damage the Automatic Recirculation Valve or disturb it'sfunction. An appropriate filtering of the medium, especially for smaller valves with lower flow rates, is
recommended (mesh width <150 µm).For the observation of the safety regulations at site the operator is responsible. The personnel must besufficiently qualified for all jobs executed at the Automatic Recirculation Valves.
For Disassembly and Assembly the security regulations listed under para 3 are to be closely
observed.
A wear of the bypass parts, especially of bypass valve head pos.12 and rotary slide valve pos.13 isfollowed by a constant leakage also when the bypass is closed. A leakage of 15 - 20 % of the minimumflow can be tolerated. When the leakage is more, the complete Bypass Valve Head (Pos. 12, 13, 14, 94.1and 94.2) is to replaced. The disassembly is described under para 14 and the assembly under para 15.If irregularities during the guarantee period occur, which make a visual inspection of the valve necessary,manufacturer and trading company are to be informed.
13. Recommendation for checking of parts subject to normal wear
Contamination and solid particles can adversely influence the function and durability of the CompensatingBypass Check Valves. During the Start-Up the parts 12 and 13 are strained especially during startingand stopping of the pump in the low load range of 75 - 140 % of the minimum flow in main delivery line.
Our general recommendation: a) Install Automatic Recirculation Valve with hand-op. Branch(see para 8)
b) Replace Bypass valve head complete during Start-up with aStart-Up-Trim (see para 7) (from PN 160)
The positions of the parts are detailled in parts list No.
In case of heavy wear at the parts 1, 2, 4 and 5 we recommend a repair of the valve in our work.
Visual inspection for wear, corrosion, erosion, pitting,
is required.1, 2, 10 After start-up or3, 4, 5, 14 regularly latest after
Part Review interval
100 Start- and Stop cycles of the pump
16, 17 12 months or 8000operating hours
12, 13 2 months or16, 17 700 operating hours or
15-20% of the minimum flow an exchange of the parts
Visual inspection for wear, corrosion, erosion, pitting,12, 13 12 months or 8000
In case of O-ring sealing the O-ring is to be replaced afterdisassembly
Start- and Stop cycles of95.3
operating hours or 100
is required.
95.1, (95.2),the pump
cavitationAt a leakage at closed bypass valve head of more than
Checking of cone seat sealing surface between pos. 1 and 3
In case of disassembly of parts 1, 2 and 10 the connecting
Checking of sealing surfaces between pos. 12, 16 and 17Checking of sealing surfaces between pos. 1 and 10
Roughness of sealing surfaces: RA=0,8µm
16, 17
24 months or
After Start-Up:
15-20% of the minimum flow an exchange of the parts
78.1, 78.2 16000 operating hours parts and maybe o-rings are to be replaced with new ones of
During Start-up until final inspection of the operator;
91.1, 91.2
Wear of the internal surfaces
cavitation
3K 195K 00104
Remark
Checking of sealing strip between pos. 1 and 2
Checking of upper and lower guides (pos. 4+5)Checking for wear of cone and lever (pos. 3 + 14)
Visual Inspection:
equal quality.
At a leakage at closed bypass valve head of more than
Because of the higher compressive force of the spring Pos.95.3 auxiliary means have to be used fordisassembly of valve size DN=150 and PN=100:
A - srewed rod
B - strap
C - nut
Pull the bypass valve head casing (Pos. 12) or Start-Up-Trim out of the lower casing (Pos. 1). If the bypassvalve head fits too tightly, it can be loosened with light hammer taps from the side.
Caution! The seal between lower casing (Pos. 1) and bypass valve head is metal-to-metal. Take
care not to damage the mating surfaces. Re-machine, if required.
Clean the parts, degrease bypass valve head. Please avoid to disassemble bypass valve head. Shouldthis be necessary, note the precise positions of parts 12, 13, and 14 in relation to one another andre-assemble exactly as before. Use a new dowel pin (Pos. 94.1). In Pos. 12 is an opening throughwhich the dowel pin 94.1 can be drifted out.
Illustration 5
constant bypassPos. 19
with
After unscrewing the four socket screws (Pos.91.2) the bypass branch (Pos.10) can be pulled off, and thethrottle (Pos.16) can be removed from the bypass branch together with the valve (Pos.17) and O-Ring(Pos.78.2). If there is a metal-to-metal sealing between throttle and bypass branch, no O-Ring is required.
A screwed rod M12 of adequate length is screwed into the valve Pos.17 and held at the flange by strapand nut. The branch can now be removed, as the spring cannot extend itself anymore. By rewinding of thenut the throttle Pos.16 slides with the valve Pos.17 out of the branch Pos.10. Caution: push against thescrewed rod, to avoid that it loosens and the spring catapults the valve away. Spring force 800 to 4000 N,depending on valve size;Recommended length of the screwed rod at
Insert the complete Bypass Valve Head into the opening of the casing. Make sure that the dowel pin 94.2is aligned with top centre. Ensure that the operating lever 14 engages in the slot of the cone stem.
Screw in connecting screws (Pos. 91.2) and tighten up with Nm tightening torque.Then remove screwed rod.
16. Disassembly of the Valve
Take valve with appropriate tools out of the piping. If lifting devicesare used, use ropes of hemp or plastic. Apply lifiting devicesaccording to illustration.
The Bypass is dismantled as per para 14.Loosen screws (Pos. 91.1) and lift off upper casing (Pos. 2)manually. Use crane for bigger valves.Remove O-Ring (Pos. 78.1) and coil spring (Pos. 95.1).
Caution, that the sealing surfaces are not damaged!
Lift out Cone - light cones manually, use lifting device forheavy cones. Use expander bolt or expander plate(see sketch).Clean and check parts. If necessary remachine metallicsurfaces at cone seat, casing split and bypass connection.Roughness Ra = 0,4 - 0,6.Build up deep indentations by deposition welding with materialNo. 1.4370 (to EN 12072: G 18 8 Mn) for unalloyed steels.Choose adequate welding alloy for chrome steel.
80
Illustration 6
Illustration 7
In case of low spring forces insert spring Pos. 95.3, valve Pos.17, O-Ring Pos.78.2 and throttle Pos.16 intobranch Pos.10 and put onto the casing. Push against spring force, srews Pos.91.2 and fasten.In case of high spring forces again use screwed bolt, strap and nut. Hold spring Pos. 95.3 with valvePos.17 in branch Pos.10, insert O-Ring Pos.78.2 and throttle Pos.16. Put the branch onto the casing,observe correct position of parts.The branch surfaces have a different distance between centers, therefore only one position is possible forinstallation. The dowel pin (Pos.94.2) must engage into the drill hole of the branch.
Insert Cone (Pos. 3), use the same tools as fordismantling. Caution! The slot in the cone stem forthe lever (Pos. 14) can be symmetrical or asymmetrical
(Illustration 7.)
If the slot is placed asymmetrically, the wider openingmust face the bypass connection (see illustration 9Section b).Insert coil spring (Pos. 95.1) and O-Ring (Pos. 78.1).If double coil spring is installed in the valve (Pos. 95.1 and95.2), please observe the appertaining parts list withadditional information regarding spring and spring washer.
Locate upper body (Pos. 2) in correct parallel alignmentand press against spring pressure. Screw in screws (Pos.91.1) and tighten up with Nm.The Bypass is to be assembled according to para 15.
Install Valve into piping. Observe Installation without tension.(see Safety Regulations).
A: Slot in cone shaft for lever (Pos.14)
B: Bypass connection
18. Notes regarding drawing and parts list
The drawing and parts list for this order are attached to this issue of Installation and OperatingInstructions. The presentation can vary slightly. The positions which have been really installed canbe seen from the parts list. Information regarding the actually installed O-Rings are to be found inpara 6. Valve Specifications.