P2.x ATEX
6.3 Replacing bellow and connecting rod-eccentric-combination
NOTICE
Restrictions for connecting rod-eccentric replacement
The individual replacement of the eccentric, connecting rod or bearings is not allowed.
Only the factory pre-assembled connecting rod-eccentric combination is suitable for re-
placement by the operator.
Please refer to assembly drawing 42/025-Z02-01-2 in the appendix for this maintenance
.
1.
Remove the three cross-tip screws (9) and remove the console cover (8) from the pump console (5)
2.
Clean any dust and other dirt off the sample gas pump. Wipe off stubborn dirt with a damp, clean cloth (do not use cleaning
products containing solvents).
Be sure to observe all notes in chapter
3.
Remove the 4 hexagon screws (16) and the spring washers (15) at the top of the pump body (13). PTFE pump bodies also have
a mounting ring (14) installed for improved seating stress.
4.
Carefully pull the pump body up and out of the pump console. Be careful not to overstretch the bellow (12). If the pump body
is stuck to the bellow, try carefully turning it to release it.
5.
Hold the bellow just above the follower (10) and unscrew it anti-clockwise. When only changing the bellow, skip to step 14.
6.
Remove the 4 hexagon screws (7) and lock washers (6) and remove the pump console from the flange.
7.
Loosen and remove the set screw (11) from the eccentric of the crank gear (10). This may either be hexagon socket (SW 2) or
star drive (TX 8). Use the proper tool.
8.
Now carefully remove the crank gear from the shaft. This is best done with 2 large slot screwdrivers.
9.
Clean the shaft and if necessary remove any residue such as frictional corrosion, etc.
Check the fit size of 11k6.
10. Dampen the shaft with resin-free oil prior to assembly.
11. Attach the new crank gear to the shaft and align the locking bore for the set screw with the corresponding bore in the shaft.
Avoid using striking tools, as these may damage the ball bearings.
12. Insert the set screw with medium-strength threadlock and tighten to 1.5 Nm. Be sure the flat point of the set screw is prop-
erly seated in the bore on the shaft.
13. Now place the pump console over the crank gear again and either align it upward or rotated by 180° and secure with the
hexagon screws (7) and lock washers (6) - tightening torque 3 Nm.
14. Check the sealing surface and the pleats of the bellow for damage and dirt.
15. Insert the bellow through the pump console from above and twist it clockwise onto the plunger of the crank gear hand
tight.
16. Clean the pump body and check the sealing face for damage.
17. Attach the pump body to the bellow and turn into the desired position in relation to the gas inlet and outlet. On principle
the alignment of the pump body is irrelevant.
However, it’s important to ensure the marking on the mounting ring or pump body matches the installed valve and its
function. There is no difference between inlet valve and outlet valve. Their installation position determines the function.
The valves are always labelled “EIN” or “IN” for inlet and “AUS” or “OUT” for outlet.
18. Reattach the pump body with the 4 hexagon screws (16) and spring washers (15) and in the case of PTFE bodies with the
mounting ring, and tighten the bolts crosswise, first at 1Nm, then 3 Nm.
19. Lastly, reattach the console cover with the 3 cross-tip screws.
20. Check the sample gas pump for leaks.
21. Perform a test run. At a minimum, the following values must be reached:
Overpressure: P2.2/P2.4 Atex = 1.7 bar; P2.72/P2.74 Atex = 1.8 bar
Negative pressure: P2.2/P2.4 Atex = -0.65 bar; P2.72/P2.74 Atex = -0.6 bar
Flow rate: P2.2/P2.4 Atex = 400 L/h; P2.72/P2.74 Atex = 700 L/h
Record the maintenance including test values in the „operating log (template)“ of the sample gas pump.
22
Bühler Technologies GmbH
BE420002 ◦ 07/2022
