1. Read the pump identification
Record the Ahlstar pump designation, serial number and seal arrangement shown in the pump documentation.
Ahlstar A, APP/NPP/WPP and older EPP/EPT variants do not all use the same stuffing-box arrangement.STUFFING BOX REFERENCE
Sulzer Ahlstar Gland Packing
Sizes, PG11 Arrangement & Service Data
For the Ahlstar PG11 gland-packing arrangement, Sulzer lists four packing rings with a lantern ring between the second and third rings. The packing cross-section depends on shaft size and ranges from 10 to 16 mm.
SCOPE
Ahlstar Packed Stuffing Box
Sulzer Version 14 documentation identifies the gland-packed arrangement as PG11. The stuffing-box data are grouped by shaft size, with four packing rings arranged around a central lantern ring and loaded by a two-piece gland.
Packing cross-section changes with shaft size: sizes 1–2 use 10 mm packing, sizes 3–4 use 12.5 mm, and sizes 5–7 use 16 mm. The table below also gives the listed shaft-sleeve diameter, stuffing-box bore and total packing length for each size.
The principal service items are gland packing 461.21, lantern ring 458.21, neck bush 456.21, stuffing-box gland 452.21 and shaft sleeve 524.21. These item numbers identify components on Sulzer drawings; the installed shaft size and seal arrangement still have to be checked before parts or packing are selected.
Older Ahlstar families and legacy EPP/EPT arrangements can use different ring counts or stuffing-box geometry. If the measured sleeve diameter, bore or packing stack differs from the PG11 data, identify the installed arrangement rather than selecting the nearest nominal size.
For ring cutting, seating and gland adjustment, use Installation. Lantern-ring position and sealing-liquid checks are covered in the Lantern Ring guide.
DIMENSIONS
Sulzer Ahlstar Gland Packing Sizes
The Ahlstar preventive-maintenance table lists the stuffing-box dimensions below for shaft sizes 1–7. In the notation d × D × a, d is the shaft-sleeve diameter, D is the stuffing-box bore and a is the square packing cross-section.
| Shaft size | Sleeve Ød | Box bore ØD | Packing section a | Listed total packing length |
|---|---|---|---|---|
| 1 | 40 mm | 60 mm | 10 mm | 640 mm |
| 2 | 50 mm | 70 mm | 10 mm | 770 mm |
| 3 | 60 mm | 85 mm | 12.5 mm | 930 mm |
| 4 | 70 mm | 95 mm | 12.5 mm | 1050 mm |
| 5 | 90 mm | 122 mm | 16 mm | 1350 mm |
| 6 | 100 mm | 132 mm | 16 mm | 1460 mm |
| 7 | 120 mm | 152 mm | 16 mm | 1710 mm |
Packing material is a separate selection. The Ahlstar dimension table defines packing size and listed length, not the packing grade. Select material for the actual fluid, temperature, solids or abrasion, shaft speed, pressure and sealing-liquid conditions. See Packing Materials for the material properties used in pump service.
Do not select from pump model alone. Ahlstar pumps exist in several families and generations. Confirm the installed shaft size and seal arrangement; if the measured sleeve or box bore does not match the table, use the actual pump documentation and dimensions.
PG11 ARRANGEMENT
TWO RINGS, LANTERN RING, TWO RINGS
Sulzer's PG11 stuffing-box arrangement uses four packing rings with the lantern ring between the second and third rings.
Sequence from the process side: neck bush → packing ring → packing ring → lantern ring → packing ring → packing ring → two-piece gland.
Part references: neck bush 456.21; gland packing 461.21; lantern ring 458.21; two-piece gland 452.21; shaft sleeve 524.21; gland nuts 920.21.
After seating the rings, align the lantern ring with the sealing-liquid passage. Keep the gland square to the shaft and tighten the gland nuts by hand before start-up.
PART IDENTIFICATION
PG11 STUFFING-BOX PARTS
Sulzer Ahlstar documentation uses the following item numbers for the packed stuffing box.
| Item | Part | Function in the packed box |
|---|---|---|
| 452.21 | Stuffing-box gland | Two-piece gland that applies axial load to the packing set. |
| 456.21 | Neck bush | Process-side component at the bottom of the sealing cavity. |
| 458.21 | Lantern ring | Distributes sealing liquid around the shaft when that arrangement is used. |
| 461.21 | Gland packing | Four compression-packing rings in the PG11 arrangement. |
| 524.21 | Shaft sleeve | Replaceable rotating surface under the packing. |
| 920.21 | Gland nuts | Move and hold the stuffing-box gland during run-in and later adjustment. |
Sulzer's 2026 Ahlstar service-kit brochure lists four packing rings together with the neck bush, shaft sleeve and lantern ring. The gland is not included in that kit listing.
IDENTIFICATION
CHECK THE INSTALLED ARRANGEMENT BEFORE ORDERING
Use the shaft-size table only after confirming the installed pump and seal arrangement. Do not order packing from the Ahlstar name alone.
2. Confirm shaft size
Use the shaft-size designation from the correct IOM or parts list. The packing section changes at shaft sizes 3 and 5.
Sizes 1–2 use 10 mm, 3–4 use 12.5 mm, and 5–7 use 16 mm in the Version 14 table.3. Measure the sleeve and bore
If the box is open, check sleeve OD and box bore. The packing section should agree with (D − d) ÷ 2.
A mismatch can indicate a different seal arrangement, older hardware or modified parts.4. Check the packing stack
Confirm four rings and the lantern-ring position before assuming PG11. Record any throat bush, modified follower or non-standard hardware.
If the installed ring count differs, identify the actual arrangement before repacking.REPACKING
CUT AND INSTALL THE RINGS
Sulzer recommends precompressed gland packing. Where packing is cut from continuous material, the Ahlstar instructions describe winding four turns around a mandrel with the same diameter as the shaft sleeve and cutting the rings cleanly.
Install the rings one at a time. Seat the first ring against the neck bush, then install the second ring with its joint displaced from the first. Fit the lantern ring, then the third and fourth packing rings. Install the last two rings with their joints 180° apart, as specified in the maintenance procedure.
Light lubrication of the sleeve and packing during assembly is specified in the maintenance procedure. Install the two-piece gland square to the shaft and bring the nuts up by hand before the first run.
For general ring cutting, seating and gland-loading practice, use the Pump Packing Installation page.
1
Clean the boxRemove used packing and clear any blocked sealing-liquid holes.
2
Inspect the sleeveReplace a sleeve with scratches or wear marks that will prevent stable packing contact.
3
Fit the neck bushPlace item 456.21 at the bottom of the sealing cavity.
4
Install two ringsSeat each packing ring individually; keep the ring joints displaced.
5
Install the lantern ringFit item 458.21 between the second and third packing rings.
6
Install two more ringsSeat the third and fourth rings without over-compressing the set.
7
Fit the gland by handKeep the two-piece gland perpendicular to the shaft and leave room for run-in adjustment.
START-UP
RUN-IN AND GLAND ADJUSTMENT
PG11 packing requires controlled leakage during run-in. After about 10 minutes of stable operation, adjust the gland evenly in about 1/6-turn increments and wait 5–10 minutes between adjustments. The Ahlstar operating instructions give an operating leakage range of 30–80 drops per minute.
| Stage | Action | What to watch | Ahlstar reference point |
|---|---|---|---|
| Initial start | Run with visible, continuous leakage. | Packing temperature and even gland position. | If leakage stops and the packing becomes hot, stop the pump and investigate the cause. |
| First 10 minutes | Let the packing run for about 10 minutes before the first adjustment. | Packing temperature, noise and continuous leakage. | First adjustment after about 10 minutes of stable operation. |
| Adjustment | Turn the gland nuts about 1/6 turn at a time. | Keep both sides even so the gland stays perpendicular to the shaft. | Wait 5–10 minutes between adjustments. |
| Operating leakage | Stop tightening when the specified leakage range is reached. | Temperature must remain stable. | 30–80 drops/min in the Ahlstar operating instructions. |
SEALING LIQUID
Seal-Water Settings Depend on the Installed Arrangement
Ahlstar instructions show several shaft-seal-fluid arrangements. Required pressure and flow depend on the installed seal configuration, not on packing size alone.
Check the connection scheme
Use the pump-specific drawing or IOM to identify whether the box uses no external sealing liquid, internal circulation or an external arrangement.
Keep the path open
During a repack, clean sealing-liquid holes and verify that the lantern ring can receive flow at its installed position.
Use the pump-specific setting
Set pressure and flow from the documentation for the installed seal configuration.
For general lantern-ring alignment and flush-path diagnosis, see Lantern Ring in Pump Packing.
OLDER CONFIGURATIONS
Legacy Ahlstar Packing Arrangements
Legacy Ahlstar manuals document several packing arrangements besides PG11. Ring count, lantern-ring position and stuffing-box dimensions can differ.
PL01–PL04Legacy APP/NPP/WPP gland-packing arrangements documented with two rings, a lantern ring and two rings.
PC01Legacy arrangement with packing and a cooling insert; do not substitute a PG11 stack without checking dimensions.
PL05Legacy EPP/EPT arrangement documented with a different ring stack and stuffing-box dimensions.
PP21Legacy EPP/EPT arrangement using a lantern ring with a different ring count from PG11.
Mismatch with the PG11 table: If the sleeve diameter, box bore or ring count differs from the Version 14 data, identify the installed arrangement before selecting packing. Do not substitute the nearest nominal size.
SERVICE CHECKS
RUN-IN PROBLEMS
| Condition | Likely effect | Check | Response |
|---|---|---|---|
| Gland too tight | High temperature, sleeve wear and increased power demand. | Leakage and gland position during run-in. | Back off the gland and restore controlled leakage. |
| No sealing-liquid path | Heat or poor packing lubrication where flushing is required. | Supply, drilling and lantern-ring communication. | Clear the path and verify the correct seal-fluid arrangement. |
| Grooved shaft sleeve | Persistent leakage and rapid packing damage. | Inspect item 524.21 after the old packing is removed. | Replace the damaged sleeve before installing a new set. |
| Leakage will not respond evenly | Cocked gland or uneven packing load. | Gland gap and nut movement on both sides. | Keep the gland perpendicular and adjust in small equal increments. |
For general leakage, heat and wear faults, see Pump Packing Troubleshooting.
ATEX: The Ahlstar Version 14 instructions state that gland packing (PG) is not to be used in explosive areas. Check the pump nameplate, sealing arrangement and current Sulzer documentation for equipment intended for a potentially explosive atmosphere.
Before ordering packing
Confirm the pump identification, shaft size, installed seal arrangement, sleeve diameter and stuffing-box bore. Use the Ahlstar size table only when those details agree with the PG11 arrangement on the pump.