ITT Flygt Mechanical Seals

1. ITT Flygt Mechanical Seals Introduction Garnitures mécaniques - Principes de base Principes de scellement ITT Flygt Garnitures mécaniques – type cartouche Matériaux Essai de qualification Service Presentation of Flygt seals. This presentation is intended to be used as a complete presentation, or as a source of slides to choose and pick from according to the purpose of the presentation.Presentation of Flygt seals. This presentation is intended to be used as a complete presentation, or as a source of slides to choose and pick from according to the purpose of the presentation.

2. The sealing system is the heart of the submersible concept. Regardless of the performance of all other systems or components, the pump, or mixer, is never more reliable than the sealing system. Not until the mechanical face seal was developed in the forties was it possible to submerge the pumps including the drive unit. The seals are highly refined wear parts relying on extreme tolerances for good performance. The tolerances must be unaffected by heat, clogging and abrasive wear for thousands of hours of operation. The demand on the sealing system in a submergible product is higher than for dry mounted pumps. Possible leakage can not be drained but accumulated in the pump until the next service. The length of the service interval is strongly dependent on expected leakage. The sealing system is the heart of the submersible concept. Regardless of the performance of all other systems or components, the pump, or mixer, is never more reliable than the sealing system. Not until the mechanical face seal was developed in the forties was it possible to submerge the pumps including the drive unit. The seals are highly refined wear parts relying on extreme tolerances for good performance. The tolerances must be unaffected by heat, clogging and abrasive wear for thousands of hours of operation. The demand on the sealing system in a submergible product is higher than for dry mounted pumps. Possible leakage can not be drained but accumulated in the pump until the next service. The length of the service interval is strongly dependent on expected leakage.

3. Garnitures Statiques et Dynamiques Seals are divided into two main groups: Static seals and Dynamic seals. Static seals has no relative motion between the sealed surfaces. Static seals, if correctly designed and maintained has no leakage. Flange packings are example of static seals. Dynamic seals are all seals that has any motion between the sealed faces. Lip seals for rotating shafts or piston seals are examples of dynamic seals. Dynamic seals always has a degree of leakage. A lubrication film must be allowed in between the sealed faces to for lubrication and ensure that the faces don’t seize. If there is a film separating the sealed faces there is also a gap between them. If there is a gap there is also a leakage. The leakage is kept a “lubrication level” and are often not perceived as leakage. The shaft seals used in submergible pumps are mechanical face seals. Since there is relative motion between the two seal rings, face seals are dynamic seals. Seals are divided into two main groups: Static seals and Dynamic seals. Static seals has no relative motion between the sealed surfaces. Static seals, if correctly designed and maintained has no leakage. Flange packings are example of static seals. Dynamic seals are all seals that has any motion between the sealed faces. Lip seals for rotating shafts or piston seals are examples of dynamic seals. Dynamic seals always has a degree of leakage. A lubrication film must be allowed in between the sealed faces to for lubrication and ensure that the faces don’t seize. If there is a film separating the sealed faces there is also a gap between them. If there is a gap there is also a leakage. The leakage is kept a “lubrication level” and are often not perceived as leakage. The shaft seals used in submergible pumps are mechanical face seals. Since there is relative motion between the two seal rings, face seals are dynamic seals.

4. Fuite The leakage is driven by the pressure difference over the seal interface. The gap between the seal faces created by the lubrication film will allow for a small transport of fluid.The leakage is driven by the pressure difference over the seal interface. The gap between the seal faces created by the lubrication film will allow for a small transport of fluid.

5. Méthodes de Lubrification The lubrication regime between the seal faces is divided into 3 type cases. Full film lubrication: A hydrodynamic lubrication film carry the load from the springs and pump pressure. No material contact between the seal faces. In this case the seal faces do not wear ( in clean Water) but will have a high leakage. Mixed film lubrication. The load from the springs and pump pressure is carried partly by the lubrication film and partly by direct material contact between the seal faces. This regime is the wanted one in a mechanical face seal. The wear and the leakage is low. Boundary lubrication: The load is carried only by direct material contact. The seal would have no leakage but would have a short operational life. The lubrication regime between the seal faces is divided into 3 type cases. Full film lubrication: A hydrodynamic lubrication film carry the load from the springs and pump pressure. No material contact between the seal faces. In this case the seal faces do not wear ( in clean Water) but will have a high leakage. Mixed film lubrication. The load from the springs and pump pressure is carried partly by the lubrication film and partly by direct material contact between the seal faces. This regime is the wanted one in a mechanical face seal. The wear and the leakage is low. Boundary lubrication: The load is carried only by direct material contact. The seal would have no leakage but would have a short operational life.

6. Surface des garnitures mécaniques The main components of a mechanical seal is two seal rings, one stationary and one rotating, with extremely flat end faces. The seal faces of the seal rings are pressed together by spring force and the pump pressure. A lubrication film, typically less than 0,5 micron thick, is formed in the sealing interface between the seal faces. The film, formed by the pump media and the buffer fluid, lubricates the seal faces preventing them from seizing. As for all dynamic seals the lubrication film will cause a minute leakage. The main components of a mechanical seal is two seal rings, one stationary and one rotating, with extremely flat end faces. The seal faces of the seal rings are pressed together by spring force and the pump pressure. A lubrication film, typically less than 0,5 micron thick, is formed in the sealing interface between the seal faces. The film, formed by the pump media and the buffer fluid, lubricates the seal faces preventing them from seizing. As for all dynamic seals the lubrication film will cause a minute leakage.

7. Surface des garnitures mécaniques The torque locks anchor the seal rings to their retaining structures. During operation the, the friction from the o-rings is sufficient to transmit the torque to the seal rings and ensure that the rotating seal ring will run with the shaft without slip, and that the stationary seal ring does not rotate in its seat. The torque locks are needed at starts after long periods of stand still. Seal ring faces, as all extremely flat surfaces, tend to stick together at stand still. A great torque is often needed at startup to break the initial sticking force to make the rings slide. Without torque locks there is a great risk that the rotating ring will remain stationary, or that the stationary ring will start rotating. The torque locks anchor the seal rings to their retaining structures. During operation the, the friction from the o-rings is sufficient to transmit the torque to the seal rings and ensure that the rotating seal ring will run with the shaft without slip, and that the stationary seal ring does not rotate in its seat. The torque locks are needed at starts after long periods of stand still. Seal ring faces, as all extremely flat surfaces, tend to stick together at stand still. A great torque is often needed at startup to break the initial sticking force to make the rings slide. Without torque locks there is a great risk that the rotating ring will remain stationary, or that the stationary ring will start rotating.

8. Fuite h represents the thickness of the lubrication film. Leakage; Q is proportional to the film thickness, h, raised to power of 3. If the film thickness is doubled, the leakage increases 23, or 8 times. It is absolutely crucial to keep the film thickness thin. Small deviation from perfect flatness or microscopic residue on the seal faces can create great leakage. The film thickness is dependent on production tolerances. Flatness and surface roughness of the seal faces must be kept within strict tolerances. Handling of the seal during service may also affect the film thickness. Even microscopic particles left on the seal faces after service may create severe leakage. h represents the thickness of the lubrication film. Leakage; Q is proportional to the film thickness, h, raised to power of 3. If the film thickness is doubled, the leakage increases 23, or 8 times. It is absolutely crucial to keep the film thickness thin. Small deviation from perfect flatness or microscopic residue on the seal faces can create great leakage. The film thickness is dependent on production tolerances. Flatness and surface roughness of the seal faces must be kept within strict tolerances. Handling of the seal during service may also affect the film thickness. Even microscopic particles left on the seal faces after service may create severe leakage.

9. Fuite As seen: 0,5 micron fluid film is acceptable, above that the leakage increases catastrophically.As seen: 0,5 micron fluid film is acceptable, above that the leakage increases catastrophically.

10. Planéité In order to achieve a thin and controlled lubrication film, the flatness tolerance of the seal face must be with within 0,6 micron.In order to achieve a thin and controlled lubrication film, the flatness tolerance of the seal face must be with within 0,6 micron.

11. Principe de scellement Flygt The sealing system is made up by: outer and inner seal, buffer fluid and an air pocket. The outer seal is exposed to the pump media and system pressure. This seal is always designed to withstand clogging and wear. The inner seal runs in a controlled environment at low pressure. Despite the lower pressure in the buffer fluid compartment, the inner seals has in general the same pressure rating as the outer seal. The buffer fluid is necessary to lubricate and cool the seal faces. The inner seal relies on cooling solely from the buffer fluid, while the outer seal is also cooled by the pump media. The air pocket is necessary to adjust for thermal volume changes of the buffer fluid. The sealing system is made up by: outer and inner seal, buffer fluid and an air pocket. The outer seal is exposed to the pump media and system pressure. This seal is always designed to withstand clogging and wear. The inner seal runs in a controlled environment at low pressure. Despite the lower pressure in the buffer fluid compartment, the inner seals has in general the same pressure rating as the outer seal. The buffer fluid is necessary to lubricate and cool the seal faces. The inner seal relies on cooling solely from the buffer fluid, while the outer seal is also cooled by the pump media. The air pocket is necessary to adjust for thermal volume changes of the buffer fluid.

12. Principe de scellement d’une pompe 3085 Sealing system in a 3085.Sealing system in a 3085.

13. Principe de scellement Flygt – Nouveaux produits The sealing system in new midrange incorporates the internal cooling system for the drive unit. The pump for propelling the coolant is an integrated part of the Plug-In seal. The buffer fluid compartment is extended to comprise the cooling channels that cools the stator. To get the best possible cooling, the buffer fluid is water with monopropylene glycol for freeze protection. The sealing system in all new products has an inspection chamber, Possible leakage through the inner seal is collected in a chamber isolated from the motor, A float switch gives a warning signal if the chamber is getting full. The sealing system in new midrange incorporates the internal cooling system for the drive unit. The pump for propelling the coolant is an integrated part of the Plug-In seal. The buffer fluid compartment is extended to comprise the cooling channels that cools the stator. To get the best possible cooling, the buffer fluid is water with monopropylene glycol for freeze protection. The sealing system in all new products has an inspection chamber, Possible leakage through the inner seal is collected in a chamber isolated from the motor, A float switch gives a warning signal if the chamber is getting full.

14. Principe de scellement d’une pompe 3153 Sealing system seen in new midrange with internal cooling system.Sealing system seen in new midrange with internal cooling system.

15. Force de fermeture positive All Flygt seals are designed and balanced for positive closing force.The higher the pump pressure the higher the Closing force. The positive closing force reduces leakage and enables high head, high submergence depth and to arrange pumps in tandem operation. Back to back seals arrangement is common in other pumps, With the outer seal back mounted, the pump pressure act to open the seal. This arrangement is uncomplicated and cost efficient, but tend to leak more and makes has a limited max head. All Flygt seals are designed and balanced for positive closing force.The higher the pump pressure the higher the Closing force. The positive closing force reduces leakage and enables high head, high submergence depth and to arrange pumps in tandem operation. Back to back seals arrangement is common in other pumps, With the outer seal back mounted, the pump pressure act to open the seal. This arrangement is uncomplicated and cost efficient, but tend to leak more and makes has a limited max head.

16. Liquide tampon It is important to fill the right amount of buffer fluid. If the level is to low, the inner seal will not get sufficient cooling and will overheat. If the level is to high, the thermal expansion of the buffer fluid will create a high pressure and possible harm the seals. It is important to fill the right amount of buffer fluid. If the level is to low, the inner seal will not get sufficient cooling and will overheat. If the level is to high, the thermal expansion of the buffer fluid will create a high pressure and possible harm the seals.

17. ’Spin-out’ A common problem in traditional bell shaped seal cavities is wear from trapped abrasive particles. If abrasive particles are present in the pump media they get trapped in the seal cavity by an interaction between the flow pattern and centrifugal force. Boundary currents close to surfaces in the cavity, indicated by red arrows, brings the particles to the inner part of the cavity. The out going current will not bring the particles all the way down to the impeller disc since the centrifugal force will transport the particles back to the in going boundary current. The particles are concentrated to the inner part of the seal cavity eroding the seal and the cavity wall. A common problem in traditional bell shaped seal cavities is wear from trapped abrasive particles. If abrasive particles are present in the pump media they get trapped in the seal cavity by an interaction between the flow pattern and centrifugal force. Boundary currents close to surfaces in the cavity, indicated by red arrows, brings the particles to the inner part of the cavity. The out going current will not bring the particles all the way down to the impeller disc since the centrifugal force will transport the particles back to the in going boundary current. The particles are concentrated to the inner part of the seal cavity eroding the seal and the cavity wall.

18. ’Spin-out’ All Flygt pumps have Spin-out seal cavities. Two (one indicated in the picture) lead the particles out from the inner part of the seal cavity and down to the impeller disc that will transport them out fro the seal area. The spin out groove does not change the general flow pattern in the seal cavity. The boundary current still transports the particles inwards, but the particles can not travel past a groove. The grooves collect them, and the rotational flow will feed them along the grooves and out of the cavity. All Flygt pumps have Spin-out seal cavities. Two (one indicated in the picture) lead the particles out from the inner part of the seal cavity and down to the impeller disc that will transport them out fro the seal area. The spin out groove does not change the general flow pattern in the seal cavity. The boundary current still transports the particles inwards, but the particles can not travel past a groove. The grooves collect them, and the rotational flow will feed them along the grooves and out of the cavity.

19. Garnitures mécanique – Type Cartouche Cut through 45 mm Plug-in seal, exposing inner seal, outer seal, springs and impeller with flow channels. All products new products, with the beginning of the 4600 mixer series are equipped with Plug-in seals. Cut through 45 mm Plug-in seal, exposing inner seal, outer seal, springs and impeller with flow channels. All products new products, with the beginning of the 4600 mixer series are equipped with Plug-in seals.

20. Garnitures mécanique – Type Cartouche Une seule pièce à installer Maintenance rapide Surfaces des garnitures mécaniques protégées Montage adéquat garantie Procédure identique pour toutes les garnitures Charge correcte et précise du ressort Pré vérifié Roue à aubes pour le refroidissement incluse Only one part to fit: Compare to traditional seals with lots of separate parts. Fast service: Easy to mount only one part with simple procedure. Protected seal faces: The seal faces on a spare part Plug-in seal are in contact from the production line. There is no possibility to contaminate the seal faces during mounting. Correct mounting: No degree of success. The seal is either correctly mounted or not mounted at all. Same procedure: The same mounting procedure applies to all 6 sizes of the Plug-in series. Spring load: The spring load is not dependant on the mounting procedure. Pre tested: Unlike traditional seals, the Plug-in seals are possible to pre test and approve before shipping, All aftermarket Plug-in seals are tested and approved. Only one part to fit: Compare to traditional seals with lots of separate parts. Fast service: Easy to mount only one part with simple procedure. Protected seal faces: The seal faces on a spare part Plug-in seal are in contact from the production line. There is no possibility to contaminate the seal faces during mounting. Correct mounting: No degree of success. The seal is either correctly mounted or not mounted at all. Same procedure: The same mounting procedure applies to all 6 sizes of the Plug-in series. Spring load: The spring load is not dependant on the mounting procedure. Pre tested: Unlike traditional seals, the Plug-in seals are possible to pre test and approve before shipping, All aftermarket Plug-in seals are tested and approved.

21. The plug-in series. 20, 25, 35, 45, 60 and 80 mm shaft diameter.The plug-in series. 20, 25, 35, 45, 60 and 80 mm shaft diameter.

22. Matériaux des anneaux des garnitures mécaniques High hardness: Resistance to wear High stiffness: To maintain flatness under load Good sliding properties: Ability to slide without seizing High thermal conductivity: Ability to conduct heat away from the seal face. Low thermal expansion: temperature gradients in the seal ring will slightly warp it. With low thermal expansion the seal face stay flat.High hardness: Resistance to wear High stiffness: To maintain flatness under load Good sliding properties: Ability to slide without seizing High thermal conductivity: Ability to conduct heat away from the seal face. Low thermal expansion: temperature gradients in the seal ring will slightly warp it. With low thermal expansion the seal face stay flat.

23. WCCR Carbure de tungstène résistante à la corrosion. Matériau de série pour les garnitures mécaniques Flygt RSiC Carbure de silicium. Matériau optionnel Al2O3Oxyde d’aluminium CCarbone. Presque éliminé. Utiliser uniquement pour les garnitures mécaniques intérieures dans les petites pompes WCCR, corrosion resistant tungsten carbide. Standard material in Flygt seals. Over all best performance of all materials. Excellent sliding properties and wear resistance. Sensitive to corrosion in pH below 3. Limited corrosion resistance in salt water RSiC, Reaction bonded silicon carbide. Optional material that is used primarily as complement to WCCR in low pH and salt water. Also excellent sliding and wear properties but sensitive to corrosion in pH exceeding 10. Al2O3, Aluminum oxide, ceramic Excellent corrosion resistance in all media up to ph 13. Not as good sliding properties as WCCR and RSiC, but a cost efficient alternative that performs well in combination with WCCR. C, carbon Carbon is a soft material and can not be used in seals exposed to the pump media. Its strengths are good dry running capability and low cost. Carbon is prone to surface pitting if used in continuous operation. Only used in small seals paired with WCCR or Aluminum oxide.WCCR, corrosion resistant tungsten carbide. Standard material in Flygt seals. Over all best performance of all materials. Excellent sliding properties and wear resistance. Sensitive to corrosion in pH below 3. Limited corrosion resistance in salt water RSiC, Reaction bonded silicon carbide. Optional material that is used primarily as complement to WCCR in low pH and salt water. Also excellent sliding and wear properties but sensitive to corrosion in pH exceeding 10. Al2O3, Aluminum oxide, ceramic Excellent corrosion resistance in all media up to ph 13. Not as good sliding properties as WCCR and RSiC, but a cost efficient alternative that performs well in combination with WCCR. C, carbon Carbon is a soft material and can not be used in seals exposed to the pump media. Its strengths are good dry running capability and low cost. Carbon is prone to surface pitting if used in continuous operation. Only used in small seals paired with WCCR or Aluminum oxide.

24. Matériaux de caoutchouc Caoutchouc fluoré (Viton) (FPM) Résistance aux températures extrêmes et bonne résistance aux agents chimiques.De série dans la plupart des garnitures mécaniques due aux températures extrêmes. Nitrile (NBR) Idéal pour la plupart des applications. Rentable Due to the friction in between the seal faces, the seal rings can reach temperatures exceeding the temperature limit of nitrile. Therefore Viton is the standard material for seal o-rings and rubber components.Due to the friction in between the seal faces, the seal rings can reach temperatures exceeding the temperature limit of nitrile. Therefore Viton is the standard material for seal o-rings and rubber components.

25. Autres matériaux Métaux Acier inoxydable AISI 329 Plastique PPS seulement (sulfure de polyphénylène). Températures extrêmes, résistant et stable. Excellente résistance aux agents chimiques The temperature limit of PPS exceeds the one of nitrile and matches the temperature limit of Viton.The temperature limit of PPS exceeds the one of nitrile and matches the temperature limit of Viton.

26. Essais de qualification Qualification testing is divided in to 3 parts. Material approval: Seal face material are approved separately with no relation to seal design. Seal design approval: New seal designs are tested and approved in lab tests. Field test. All seal designs are tested and approved for each product in witch it should be used.Qualification testing is divided in to 3 parts. Material approval: Seal face material are approved separately with no relation to seal design. Seal design approval: New seal designs are tested and approved in lab tests. Field test. All seal designs are tested and approved for each product in witch it should be used.

27. Essais de qualification

28. Essais de qualification

29. Maintenance Seals that has been in operation for some time, typically a week, should not be re-mounted if it has been removed from the pump during service. Even if the seal faces looks fine to the naked eye, there is a great likelihood that the seal faces has worn in to each other and that the seal will leak if re-mounted. Seals that has been in operation for some time, typically a week, should not be re-mounted if it has been removed from the pump during service. Even if the seal faces looks fine to the naked eye, there is a great likelihood that the seal faces has worn in to each other and that the seal will leak if re-mounted.

30. Maintenance Each spare part seal is delivered with a mounting instruction. The mounting instruction show how to mount the seal and which tools to use. It also specifies where to lubricate with oil and where to lubricate with grease. Oil is represented by an oil can, and grease with a grease gun. It is important that the instruction is flowed. Each spare part seal is delivered with a mounting instruction. The mounting instruction show how to mount the seal and which tools to use. It also specifies where to lubricate with oil and where to lubricate with grease. Oil is represented by an oil can, and grease with a grease gun. It is important that the instruction is flowed.

31. Maintenance

32. Maintenance

33. Maintenance

34. Maintenance Lubrifiez l’arbre moteur The dynamic o-ring must be able to slide with low friction to allow the spring to adjust for run-out and shaft deflection. The best way to apply grease is on the surface on which the o-ring slide. The dynamic o-ring for 3085 slides on the shaft. Therefore; grease the shaft and let the o-ring collect the greases when is slid over it during mounting. The outer seal for 3140-3300 has the dynamic o-ring on the stationary seal ring. Grease the o-ring and the surface on the seal ring on which it seals. The dynamic o-ring must be able to slide with low friction to allow the spring to adjust for run-out and shaft deflection. The best way to apply grease is on the surface on which the o-ring slide. The dynamic o-ring for 3085 slides on the shaft. Therefore; grease the shaft and let the o-ring collect the greases when is slid over it during mounting. The outer seal for 3140-3300 has the dynamic o-ring on the stationary seal ring. Grease the o-ring and the surface on the seal ring on which it seals.

35. Maintenance Appliquez quelques gouttes d’huile sur la surface de la garniture mécanique afin de prévenir le collage avec l’autre surface

36. Maintenance Mettre la partie rotative en place

37. Maintenance Appliquez une force maximum de 20 Newton sur l’outil de montage lors de l’installation de l’anneau de retenue If too high force is used when the grip ring is released, the seal might be compressed to far and the seal faces overloaded. If the position of the grip ring needs to be adjusted, DO NOT tap in to position. Dismount the seal and start over. If too high force is used when the grip ring is released, the seal might be compressed to far and the seal faces overloaded. If the position of the grip ring needs to be adjusted, DO NOT tap in to position. Dismount the seal and start over.

38. Maintenance Vérifiez le dégagement If the stop ring can be pushed down so it just clears the grip ring the axial positioning is right. If the stop ring can be pushed down so it just clears the grip ring the axial positioning is right.

39. Maintenance Vérifiez le boîtiez de la garniture mécanique et l’abre moteur pour tout dommage. Lubrifiez l’arbre moteur. The shaft should be greased so that the dynamic o-ring for the inner seal of the Plug-in unit gets lubricated.The shaft should be greased so that the dynamic o-ring for the inner seal of the Plug-in unit gets lubricated.

40. Maintenance Appliquez de l’huile sur le joint torique stationnaire

41. Maintenance Mettre la garniture mécanique (type cartouche) en place. Assurez-vous que la barrure anti-rotation est dans la bonne position.

42. Maintenance Installez l’anneau de retenue, assurez-vous qu’il entre dans la cannelure de l’arbre moteur The retaining ring groove is of conical design. It is made conical so that the retaining ring rides on the conical flange and fasten the drive with absolutely no play. This is done to eliminate run out. Give the retaining ring a couple of nudges from each side to help it as far in to the groove as possible.The retaining ring groove is of conical design. It is made conical so that the retaining ring rides on the conical flange and fasten the drive with absolutely no play. This is done to eliminate run out. Give the retaining ring a couple of nudges from each side to help it as far in to the groove as possible.

43. Maintenance Don’t forget the o-ring in the seal housing cover.Don’t forget the o-ring in the seal housing cover.

44. Maintenance Fix the Plug-in seal with the seal housing cover.Fix the Plug-in seal with the seal housing cover.

45. Maintenance Appliquez de la graisse sur l’anneau de retenue afin de le protéger de la corrosion

46. Tolérances de gauchissement Seal leakage be caused by other factors than the seal itself. If the same pump has had a history of seal leakage several times despite seal change, it could be a good idea to check the shaft run-out. Allowed run-out is specified in the table.Seal leakage be caused by other factors than the seal itself. If the same pump has had a history of seal leakage several times despite seal change, it could be a good idea to check the shaft run-out. Allowed run-out is specified in the table.

47. Maintenance Les garnitures mécaniques peuvent être opérées à sec si la pompe ou agitateur contient la quantité appropriée de liquide tampon. L’opération à sec devrait être limité à quelques minutes pour les garnitures mécaniques montées sur des arbres moteurs de 80mm et plus afin d’éviter une surchauffe Dry test run of the pump after service is OK if the oil housing is filled with the correct amount of buffer fluid. If the pump is run without buffer fluid, the seals will overheat in matters of seconds.Dry test run of the pump after service is OK if the oil housing is filled with the correct amount of buffer fluid. If the pump is run without buffer fluid, the seals will overheat in matters of seconds.

48. Contrôle d’étanchéité ?Pmax=0,017*Po*t/V [bar] ?Pmax=Chutte de pression Po=pression a l’intérieur de l’unité de test [bar] t =Durée du test [min] V =volume de l’unité de test [l] The seal housing should be free of buffer fluid during the tightness check. The total volume of the seal housing is approximately the specified oil volume times 1.2. The seal housing should be free of buffer fluid during the tightness check. The total volume of the seal housing is approximately the specified oil volume times 1.2.

49. – Aucun souci Garnitures mécanique Flygt