Carrier 5H40-276 Shaft Seal Assembly

Carrier 5H40-276 Shaft Seal Assembly (MPN: 5H40-276 / 5H40276)

The Carrier / Carlyle 5H40-276 Shaft Seal Assembly is an engineered mechanical sealing solution built for open-drive reciprocating refrigeration compressors operating under severe industrial and marine duties. Designed specifically for Carlyle 5H-series platforms (including 5H40, 5H60, and 5H80 models), this assembly establishes an absolute barrier preventing refrigerant charge escape and atmospheric air/moisture ingress along the rotating crankshaft journal.

Constructed with precision-lapped contact faces and a resilient spring/bellows loading mechanism, the 5H40-276 compensates for angular crankshaft deflections, thermal expansions, and axial thrust variances common during variable-load chiller and marine cargo operations. It provides continuous containment across positive crankcase pressures as well as deep-vacuum pump-down cycles.

Model Details

• Manufacturer: Carrier Corporation / Carlyle Compressor Division
• Manufacturer Part Number (MPN): 5H40-276 / 5H40276
• NATO Stock Number (NSN): 4320-00-462-2248
• HS / Tariff Code: 4016.93.00 / 8414.90.41
• Assembly Includes: Mechanical bellows/spring rotating seal assembly, precision carbon/friction washer nose, statutory stationary mating seat, casing cover gasket, and specialized elastomer seal rings.

Technical Specifications

Key Features

1. Precision-Lapped Sealing Interfaces: Micro-finished contact faces engineered to sub-micron flatness tolerances eliminate micro-channel refrigerant leakage under both positive crankcase pressures and vacuum conditions.
2. Metal Bellows Dynamic Compensation: Mechanical spring loading automatically absorbs dynamic crankshaft runout, thermal growth, and cyclic vibrations without face-tracking loss.
3. High Chemical Compatibility: Elastomers and metallic components withstand continuous exposure to synthetic POE, alkylbenzene, and mineral refrigeration lubricants without hardening or volumetric degradation.
4. Bi-Directional Sealing Integrity: Holds seal tight against internal crankcase pressures up to 30.0 bar (435 psig) while preventing air and moisture ingress during sub-atmospheric suction operations.

Applications

• Marine Refrigeration & Provision Systems: Reefer cargo holds, galley provision plants, and sea-water chiller sets on commercial cargo vessels, tankers, and offshore platforms.
• Industrial HVAC & Water Chillers: Heavy commercial built-up air handling, industrial process cooling, and district cooling systems utilizing open-drive Carlyle 5H compressors.
• Cold Storage & Flash Freezing Facilities: Industrial low-temperature and medium-temperature blast freezers, agricultural packing houses, and controlled-atmosphere storage.
• Process Gas Compression & Petrochemical HVAC: Hazardous-area and continuous-duty process refrigeration setups requiring stable mechanical containment.

Compatible Compressor Models

• Carrier / Carlyle 5H Series: 5H40, 5H46, 5H60, 5H66, 5H80, 5H86, 5H120, 5H126 (all standard and long-stroke open-drive reciprocating variants).
• Specific Sub-Models: 5H80-A219, 5H60-C109, 5H40-149, among other marine and industrial baseline frames.
• Licensed Equivalents: Voltas 5H-series open-type reciprocating compressor units.

Marine Chief Engineer’s Guide

Field Directive from the Engine Room: A mechanical shaft seal requires spotless installation conditions. More than 80% of open-drive seal replacements leak within 48 hours not because of part defects, but due to dry-face initial starts, debris on the lapped surfaces, or improper torque loading on the seal housing cover plate.

• Shaft Cleanliness & Runout Inspection: Before sliding on the new seal assembly, polish the crankshaft sleeve using a 600+ grit crocus cloth. Use a dial indicator to confirm total indicated radial runout (TIR) on the shaft does not exceed 0.05 mm (0.002 in). Any micro-grooving will compromise the internal elastomer sleeve.
• Pre-Lubrication Protocol: Never install dry. Generously coat the carbon nose and stationary metallic lapped face with clean, dry compressor oil matching the system charge (e.g., POE 68 or Mineral ISO 32/46/68).
• Cross-Star Torque Pattern: Hand-tighten cover plate bolts first, then tighten in a cross-star pattern across three torque stages to the final factory specification (34–41 Nm / 25–30 ft-lbs). Uneven torquing distorts the stationary seat and creates localized face separation.
• Vacuum Decay & Oil Level Confirmation: Pull down the compressor block to below 500 microns and perform a 30-minute standing vacuum hold before opening the isolation service valves. Confirm the oil level is at least half-glass high in the sight window prior to energizing the prime mover.

Frequently Asked Questions

What is the function of the Carrier 5H40-276 shaft seal assembly?

The 5H40-276 shaft seal creates a dynamic pressure barrier around the rotating crankshaft of Carrier Carlyle 5H open-drive compressors. It prevents pressurized refrigerant and compressor oil from escaping into the environment while preventing atmospheric air, oxygen, and moisture from entering the system under vacuum.

Can the Carrier 5H40-276 seal be used with R134a and POE oils?

Yes. While originally designed for standard R22 and R12 operations, the metal bellows and modern synthetic elastomer packaging are chemically compatible with retrofit HFC systems utilizing R134a, R404A, R407C, and polyolester (POE) refrigeration lubricants.

What causes premature seal face leakage on Carlyle 5H compressors?

Premature failure typically results from: dry rotation during initial startup, thermal degradation caused by continuous crankcase temperatures above 77°C (170°F), particulate contamination in the lubricating oil, or misaligned coupling installation that exceeds allowable crankshaft radial runout.

Is it possible to replace only the carbon ring instead of the entire assembly?

No. It is standard engineering practice to replace the entire 5H40-276 kit—including the dynamic bellows assembly, stationary seat, carbon washer, and gaskets. Mating surfaces wear together, and swapping individual parts often results in imperfect face alignment and rapid refrigerant loss.

How do I verify if my compressor takes the 5H40-276 seal?

Check your compressor serial/model data plate. If your model starts with 5H40, 5H46, 5H60, 5H66, 5H80, or 5H86, the 5H40-276 is the direct factory-specified shaft seal assembly. Always verify shaft diameter and casting part numbers prior to assembly overhaul.