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Gemini Next-gen h302 & H304 Upgrade Kits

An upgrade set as the engineering standard for the protection of power pistons
for large bore compression and power generation engines.
Cooper Machinery Services Emerging Legends Series Logo

upgrade kits for Gemini 3-stage compressors

Cooper is pleased to introduce the next generation of Gemini compressors with the release of the H302 and H304 upgrade kits for Gemini 3-stage compressors. These kits are designed to enhance the performance, reliability, and durability of your existing Gemini compressors.


The complete upgrade kits are primarily designed for high-pressure gas lift applications, specifically for Gemini H-series, 3-stage compressors with a 7.5″ x 5″ x 3″ compressor
cylinder configuration. Cooper also offers separate part options for tailored solutions.


The upgrade kits enhance the overall performance and reliability of your Gemini 3-stage compressors, ensuring smoother operation and consistent results.

The piston profile and piston rings have been modified to extend the life of the cylinder, reducing maintenance costs and downtime.

The upgrade kits have strengthened connection hardware that provides more rigidity on the distance piece to cylinder body connections, as well as an improved tandem cylinder connection design to ensure a robust and secure assembly under heightened stress operating conditions.

Innovative upgrades to Cooper’s compression cylinder valves and combination ring assemblies reduce the frequency of valve and piston ring maintenance and replacements, resulting in cost savings and increased operational efficiency.

Redesigned piston ring configurations and upgraded compressor valves reduce the compression horsepower requirements, improving overall efficiency of your compressor.

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Cooper’s Gemini Next-Gen H302 & H304 upgrade kits are a member of the Emerging Legends™ Series, our portfolio of new products and services that advance the industry and transform Cooper’s traditional way of doing business. Emerging Legends™ serves as a testament to the Cooper commitment of optimizing performance of legacy engines and compressors, helping our customers extend the life of their equipment, and bringing environmentally sustainable solutions to the market.

Upgrade Summary

The Next-Gen Gemini H302 & H304 upgrade kits offer a comprehensive range of enhancements to improve your compressor performance. These include redesigned pistons that accommodate new combination compression and rider rings for optimized efficiency and reduced maintenance intervals, a redesigned 2nd stage compressor cylinder for enhanced durability, and CP compressor cylinder valves to reduce maintenance and replacements. Further improvements to the frame, cylinder body, and valve cap connection hardware ensure superior structural integrity. Additionally, valve chairs and covers are modified for enhanced functionality. These upgrades enable Gemini compressors to perform at their peak, thereby reducing maintenance, improving operational efficiency, reducing costs, and delivering exceptional results.

New part #DescriptionDetailed Description
ZKIT-2023-005-UPGDComplete H-302 Compressor
Upgrade Kit
Full Upgrade Kit to convert a legacy H-302
(7.5" x 5" x 3") to the new "Next Gen H-302"
ZKIT-455-0003-UPGDH & M Compressor Auxiliary Cover
Upgrade Kit
Kit to upgrade the auxiliary end cover assembly to the current design
(helical gear, solid cam for lubricator pump and sight glass)
ZKIT-7.5-PSTN-UPGD7.5" Cylinder Piston/Piston Ring
Upgrade Kit
Kit to upgrade the 1st stage piston to new combo ring design.
This includes new piston, piston rings, counterweights, and hardware.
ZKIT-7.5-CYL-UPGD7.5" Cylinder Hardware
Upgrade Kit
Kit to upgrade the studs from the cylinder to guide (reduced shank studs).
Also includes nuts and an O-ring seal.
ZKIT-7.5-VLV-UPGD7.5" Cylinder Compressor Valve
Upgrade Kit
Kit to upgrade the 1st stage compressor cylinders with new CP valves.
ZKIT-5-3-PSTN-UPGD5" & 3" Tandem Cylinder Piston/Piston Ring
Upgrade Kit
Kit to upgrade the 2nd and 3rd stage pistons to new combo ring
design. This includes new piston, piston rings, counterweights,
and hardware.
ZKIT-5-3-CYL-UPGD5" Cylinder Body & Hardware
Upgrade Kit
Kit to upgrade the 2nd stage cylinder half to new thru stud
design. Also includes seals and hardware for mounting.
ZKIT-5-3-VLV-UPGD5" & 3" Tandem Cylinder Compressor Valve Upgrade KitKit to upgrade the 2nd and 3rd stage compressor cylinders with new CP valves.