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NAF-Turnex pneumatic actuators
User Manual
20 pgs5.59 Mb0

Flowserve NAF-Turnex pneumatic actuators User Manual

NAF-Turnex pneumatic actuators
NAF 791290/92/94, sizes 0, 1-3 and 4-5 Maintenance instructions and spare parts list
Contents
General ........................................................... 1
Maintenance ..................................... 2
To change the piston rod bearings, size 0 .......................... 2.3
To change the piston rod seal, sizes 1-3
To change the PTFE-coated bushes ................................... 2.5
Actuator with spring return .................... 3
To dismantle and assemble the spring-
To dismantle the spring-return unit .................................... 3.3
To assemble the spring-return unit .................................... 3.4
Accessories ...................................... 4
Fitting the end position sensor ........................................... 4.2.1
Valve positioner .................................................................
Spare parts ....................................... 5
Spare parts kits, sizes 4-5 .................................................. 5.3
4.5
Fi 74.59(3)GB
05.12
Size 0
Size 1 - 3
Parts list .......................................... 6
Double-acting actuator, sizes 0 and 1-3 ............................. 6.1
Single-acting actuator, sizes 0 and 1-3 .............................. 6.2
1. General
The actuators are designed to withstand a long period of continuous operation at high loading, normally without the need for servicing.
Air or an inert gas must be used as the actuating medium. The air must be dried and thoroughly cleaned to prevent wear of the cylinder bores, pistons and sealing rings. Oil mist lubrication of the actuating medium is not recommended. The maximum permissible pressure of the actuating medium is 0.8 MPa (8 bar) and the maximum permissable temperature is 80°C.
From the operating viewpoint, the actuator can be installed in any position. However, it must not be subjected to excessive radiant heat, vibrations or other adverse circumstances that could damage its components.
Size 4 - 5
The actuator delivered from NAF AB is in fully operational condition. For particulars of the correct connection/ commissioning, refer to the commissioning instructions Fi 74.562 iGB.
These actuators normally require little or no maintenance. However, after a long period of service, certain parts may become worn or damaged, and will then have to be replaced.
To minimize the time needed for overhaul or repair, it is advisable to keep a suitable stock of spare parts. These are available as individual components, but it is economically preferable to purchase the spare parts kits recommended by NAF, the compositions of which are matched to different overhaul levels.
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2. Maintenance
It the air consumption of the actuator is abnormally high or if its operating speed is low, this may be due to wear or damage to the cylinders, pistons or sealing rings. The bearings, bushes and guide rings may also be worn or damaged.
The actuator must be removed from the valve for over­haul and repair!
2.1 Dismantling
Dismantling of the actuator is described below. The item numbers within brackets refer to Fig. 19.9, 19.1 and 19.4 on pages 17, 18 and 19.
Dismantling and maintenace of actuators with spring return must be carried out as described in section 3. Note that the actuator must be depressurized before it is dismantled!
Size 0 (Fig. 19.0)
1. Release the bolts (2) and remove them together with the washers (59. The end covers (4) with their O-rings (3) can now be removed. Also remove the cylinders (1, 16) by withdrawing them from the housing (30).
2. Remove the screws (18) form teh top and underside of the actuator. Then remove the cover (29) and base (74).
3. Remove either of the circlips (11) and press out the pin (10). Now lift out the entire linkage mechanism (Fig. 1.0) from the actuator, but don´t start dismantling it just yet.
4. If the actuator has two pistons (25), fit a ring spanner to each piston nut (24), and then turn the spanners anti-clockwise until one of the nuts is released. Remove the nut, washer (24.1) and piston (25). Then withdraw the piston rod (26) from the actuator.
Fig. 1.0. Linkage mechanism, size 0
After inspecting for damage and wear in accordance with section 2.2, re-assemble the actuator as described in section 2.6.
Size 1-3 (Fig. 19.0)
1. Release the nuts (6) and remove them together with the washers (5). The end covers (4), cylinders (1, 16) and O-rings (3) can now be removed.
2. Remove the screws (18) from the top and underside of the actuator. Then remove the cover (29).
3. Rotate the threaded pin (10), and then withdraw it straight out of the coupling (31).
4. If the actuator has two pistons (25), fit a ring spanner to each piston nut (24), and then turn the spanners anti-clockwise until one of the nuts is released. Remove the nut, washer (24.1) and piston (25). Then carefully withdraw the piston rod (26) from the actuator.
5. The linkage mechanism (Fig. 1.1) can now be lifted out of the actuator (Fig. 2.1). Further dismantling of the linkage mechanism is not normally necessary. See section 2.2
Fig.1.1. Linkage mechanism, size 1 - 3
M5/M8 screw
Link (8)
Pin (9)
Locking clip (10A)
Fig.1.4. Linkage mechanism, sizes 4 - 5
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Fig. 2.1. NAF-Turnex, sizes 1 - 3
Sizes 4-5 (Fig. 19.4)
1. Remove the air cylinder retaining bolts (12) and carefully remove the cylinder.
2. Withdraw the cylinder straight up.
3. Remove the locking screws (45) and remove the cover (2).
4. Release the locking links (8) as shown in Fig. 1.4 and Fig. 19.4 by prising apart the locking clip (10A) by means fo circlip pliers, and withdraw the pins (9A) by means of a screw (M5/M8) screwed into them.
5. Turn the links so that the lever lugs are exposed and lift out the lever.
6. If the actuator has two pistons (32), fit a ring spanner to each of the piston nuts (36) and then turn the spanners anti-clockwise until one of the nuts is released. Remove the nut and the piston.
N.B. Never use the piston or piston rod as restraint
for releasing the other piston unit. Take a slit nut instead (with a slit width of 2-3 mm), and screw it onto the free end of the piston rod. Grip the slit nut with the pipe wrench and restrain it while releasing the other piston nut.
Take care not to scratch the piston rod. Scratches could cause damage to the piston rod seal.
7. If the actuator has only one piston, remove the piston nut by means of a slit nut as described above.
8. Remove the screws (14) from the coupling (25).
9. Pull away the coupling (25) and use circlip pliers to open up the circlip (26). At the same time, carefully withdraw the piston rod (31) from the seal holders (42), couplings (25 and 27) and circlip (26).
Inspect for damage and wear in accordance with section
2.2. Re-assemble the actuator as described in section 2.6.
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2.2 Checking for damage and wear
Size 0
The following parts should always be replaced: Lever bearings (38) O-rings (3, 7, 17, 27, 37) If the air consumption of the actuator is abnormally high, this may be due to wear of the O-ring (27). Always replace it as stated above. The following parts should also be inspected:
Cylinders (1, 16). Clean the cylinders with white spirit and blow them dry with compressed air. Inspect the cylinder bore for scratches and other internal damage. Fit a new cylinder if the existing one is damaged.
Pistons (25). Inspect the sealing lips of the piston. If these are damaged or heavily worn, fit a new piston. If one of the pistons is still on the piston rod, it can be removed by fitting two nuts to the opposite end of the piston rod (26) and locking them against one another. The inner of the two nuts can then serve as a restraint when the nut (24) at the opposite end of the piston rod is released with a ring spanner. Take care not to damage the piston rod surfaces.
Piston rod (26). If the piston rod has deep longitudinal scratches, the piston rod and piston rod bushes (28) must be replaced. However, minor scratches on the piston rod can be removed by carefully rubbing down with very fine emery cloth.
Size 1-3
The following parts should always be replaced: Lever bearings (38) O-rings (3, 7, 17, 37) If the air consumption of the actuator is abnormally high, check the following parts:
Sizes 4-5
The following parts should always be replaced: Lever bearings (4, 16) O-rings (7, 17, 30, 43) If the air consumption of the actuator is abnormally high, check the following parts:
Cylinders (35). Clean the cylinders with white spirit and blow them dry with compressed air. Inspect the cylinder bore for scratches and other internal damage. Fit a new cylinder if the existing one is damaged.
Lever (6) bearings (3, 4,10 and 16). Clean the bearings with white spirit, and fit new bearings if there is play in the existing bearings. Inspect the O-rings (7 and 17). Fit new O-rings if necessary. Grease the O-rings and bearings surfaces. Re-assemble.
Pistons (32). Inspect the piston guide ring (33) and faced O-ring (34). Fit new rings if the existing ones are scratched or haved damaged edges, or if they are heavily worn. If no damage is visible, test the outside dimensions of the sealing ring by threading the cylinder onto the piston. If this is easy to do without significant resistance, this indicates that the O-ring and guide ring are heavily worn and new ones must be fitted.
Use a small screwdriver to prise carefully the old guide ring and faced O-ring. Place the new rings for 3-4 minutes in water at 60°C to soften them. Then quickly prise the
ringsover the guide edge of the piston and down into the groove. Don´t use tools with sharp edges, and don´t stretch the rings more than necessary, since they could otherwise be permanently deformed. The simplest procedure is to fit a spare piston and send the damaged piston back to NAF for replacement of the rings. This has the added benefit of a factory guarantee.
Cylinders (1, 16). Clean the cylinders with white spirit and blow them dry with compressed air. Inspect the cylinder bore for scratches and other internal damage. Fit a new cylinder if the existing one is damaged.
Pistons (25). Inspect the sealing lips of the piston. If these are damaged or heavily worn, fit a new piston. If one of the pistons still remains on the piston rod, it can be removed by fitting two nuts to the opposite end of the piston rod (26) and locking them against one another. The inner of these two nuts can then serve as a restraint when the nut (24) at the opposite end of the piston rod is released with a ring spanner. Take care not to damage the piston rod surfaces.
Piston rod seals (27). Inspect these for damage or find out whether the piston rod (26) moves very freely in the seals. If the seals are damaged or leaking, fit new seals. See section 2.4
Piston rod (26). If the piston rod has deep longitudinal scratches, a new piston rod must be fitted. Minor scratches can be removed by carefully rubbing down with very fine emery cloth.
Piston rod seals (42). Inspect these for damage or find out whether the piston rod (31) moves very freely in the seals. If the seals are damaged or leaking, fit new seals. See section 2.4
Piston rod (31). If the piston rod has deep longitudinal scratches, a new piston rod and piston rod bearings (44) must be fitted. Minor scratches can be removed by carefylly rubbing down the piston rods with very fine emery cloth.
Sizes 0-3 and 4-5 After a long period of service under difficult conditions, it may be necessary to change other component parts. Check the following:
Piston rod bearings (item 28 of sizes 0 and 1-3, and item 44 of sizes 4-5). If the internal PTFE coating is
damaged so that the metal to which it has been applied is visible through the coating, fit new bearings. See section
2.3. Linkage mechanism - Fig. 1. This consists mainly of
pins, links, lever and coupling. If play can be felt in the mechanism or if there is reason to suspect that some part may be damaged, the mechanism should be dismantled.
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Remove the circlips (11 and 22, or 19 and locking clip 10A). The figures refer to sizes 0-3 and 4-5 respectively. The pins and links can now be removed.
Now check the following parts:
Pins (23 and 9A). If these are damaged or heavily scratched, fit new pins. Minor scratches can be removed by rubbing down with very fine emery cloth.
Links (12-14 and 8A). The link includes one or two bushes (14 or 18 respectively) of Glacier manufacture. This does not apply to size 3 actuator, in which the bushes are fitted into the link. If the internal PTFE coating is damaged so that the metal to which it has been applied is visible through the coating, fit new bushes. See section
2.5.
Lever (21 and 6). The lever includes two bushes (21.1 or 11 respectively) of Glacier manufacture. This does not apply to size 3 actuator, in which the bushes are fitted into the link. If the internal PTFE coating is damaged so that the metal to which it has been applied is visible through the coating, fit new bushes. See section 2.5.
The coupling (31 or 25 and 27).
coupling. If these are damaged or heavily scratched, a new coupling must be fitted. Minor scratches can be removed by rubbing down with very fine emery cloth.
Check the pins of the
2.3 To change the piston rod bearings
Size 0
To remove the piston rod bearing (28), insert a small screwdriver between the bearing and the outside of the housing (30) and prise away the bearing (see Fig.3). Press in a new bearing. This is best done in a vice and should be done quickly so that the bearing will not deform plastically. After fitting, the bearing should be free to rotate in the housing, but should be locked in the axial direction.
2. Clean the groove with white spirit and wipe it clean.
3. Fit the O-ring of the piston rod seal or, on sizes 4-5, fit a complete seal holder (42).
4. On sizes piston rod seal in water at 60°C for 3-4 minutes, so that
it will soften.
Fig. 4. Forming the PTFE ring for the piston rod
5. Grip the ring with your fingers and form it into the shape shown in Fig. 4.
6. Fit the PTFE ring into the groove and press it back into its circular shape.
7. Check that the piston rod (26 or 31) is free from scratches or burrs. If not, use very fine emery cloth to remove them before fitting the pison rod. Clean the piston rod with white spirit and then wipe it with a piece of lint-free linen cloth.
8. On leave it there for at least 10 minutes. The PTFE ring will then have resumed its original shape and the piston rod can be removed.
9. On sizes 4-5, fit a complete new seal holder (42). Apply locking compound to the screws and tighten them.
1-3, place the PTFE ring (27) of the O-ring
sizes 1-3, push the piston rod into the seals and
2.5 To change the PTFE-coated bushes
Size 0
A drift is needed for changing only the bushes (14) in the links (12). Make a drift as shown in Fig.5. Use the drift and a mallet to remove the worn bushes. Use the same drift to fit the new bushes, using a vice for the purpose. However, we recommend that the entire link should be replaced by a new one.
Fig. 3. Removing the piston rod bearing
2.4 To change the piston rod seal
Size 1-3 and 4-5
The actuator must be dismantled as described in section
2.1.
1. On sizes 1-3, remove the old piston rod seal (27 or
42) by means of a small screwdriver, for instance. If the piston rod bearing is to be replaced, this must be done as described in section 2.5 before continuing.
Fig. 5. Changing the bushes in a link Sizes 1-3 and 4-5
The piston rod bearings (28 or 44), lever bush (21.1 or
18) and link bush (14 or 11) may have to be changed after a long period of service under difficult conditions. Replacement must be carried out when the PTFE coating has become worn so that the metal to which it has been applied is visible through the coating.
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1. To remove the bush. The easiest procedure is to
make a drift as shown in Fig.6 for link and lever bushes, and a drift as shown in Fig.7 for the piston rod bearing. The bush can then easily be removed by means of this drift and a mallet.
2. To fit new bushes. To fit the new bushes (21.1 or 18) into the lever and new bushes (14 or 11) into the links, use the same drift as that used for removing them. Use the drift and a vice, for instance, to press in the bush. The easiest way of fitting the piston rod bush (28 or 44) is to press it in by means of a bolt as shown in Fig.8.
Fig. 6. Drift for the bushes
Fig. 7. Drift for the piston rod bearing
Fig. 8. Fitting the piston rod bush
2.6 Assembly
Grease part No. 349 06 260, which has been tested by NAF and a leading lubricant manufacturer, is recommended for all surfaces that require greasing. This grease has proved to have by far the best properties for lubricating the contact surfaces between rubber/plastic and metal. These properties include high load-bearing capacity, good adhesion, and very low stick-slip effect.
Size 0
1. Make sure that all parts have been thoroughly cleaned. Wipe clean the cylinders (1, 16), bearing surfaces of the lever (21), and other sliding surfaces.
2. If the linkage mechanism (Fig.1) has been dismantled, re-assemble it. Fit the links (12, including the bushes
14) to the lever (21) using the pins (23) and circlips (22).
3. Grease the O-rings (37) and fit them onto the lever (21).
4. Grease the O-rings (27) and fit them into the piston rod bearings (28).
5. Rub a thin layer of grease onto the piston rod (26). Carefully push the piston rod into the bearing (28), past the O-ring (27) and out through the corresponding bearing on the other side of the housing.
N.B. The location of the hole in the piston rod is not sym­metrical. The side of the piston rod which is longer (from the hole to the end) should be located on side A as shown in Fig. 19.0.
6. Coat the lips of the piston (25) with a thin film of grease, and make sure that the groove between the lips is filled with grease as shown in Fig. 9. Fit the pistons to the piston rod (26) with the rubbercoated side facing the nut. Apply locking compound to the piston rod thread. Fit the washer (24.1) and nut (24). When the pistons have been fitted, tighten the nuts simultaneously to the torque specified in Table 1.
7. Place the linkage mechanism (Fig.1) as shown in Fig.19.0. Fit one of the circlips (11) to the pin (10). Then push the pin in through the links (12) and piston rod (26), and lock the pin with the other circlip (11).
8. Fit the lever bearings (38) into the cover (29) and base (74). The easiest procedure for fitting the bearings is by using a press or a vice.
9. Apply a little medium-strength locking compound into the tapped holes, and use the screws (18) to secure the cover (29) and base (74). See Table 1.
N.B. Fit the cover and base as shown in Fig. 19.0, so that the linkage mechanism will open in the right direction.
10. Grease the O-rings (3, 17) and fit them into the piston rod bearings (28) and housing (30) respectively. Two of the O-rings (3) will be left over and can then be used in the end cover (4).
11. Apply a thin coat of grease to the surfaces of the cylinders (1, 16). Work the grease into the whole of the sliding surface by means of a clean piece of lint­ free linen cloth. Carefully push the cylinders onto the pistons.
12. Fit the remaining two O-rings (3) into the end covers (4) and place the covers on teh cylinders. Apply a little medium-strength locking compound into the M6 tapped holes at the cylinders. Fit the washers (5) and bolts (2). Tighten the bolts in diagonally opposite pairs (see Table 1). The tightening torque corresponds to tightening the bolts by hand until they come into contact with the end cover, and then tightening about a further quarter of a turn.
N.B. It is important not to overtighten the bolts since the tapped holes in the housing may otherwise be damaged.
13. Adjust the end-stop bolt (9) to the required end position.
Part Actuator size
0 1 2 3
Piston rod nut (24, 56) 14 29 50 115 Pin (10) 7 50 115 Tie-rod nut (6) 7 35 35 Locking screw (18) 17 7 17 17 End-cover bolt (2) 7
Table 1. Tightening torques, Nm, for the bolts and nuts of the actuator
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