Specific pattern of failure, US Sankey /D System valves
Over the past year I have been made aware of many two- to five-year old D System (US Sankey) keg valves failing in a specific way in breweries in the US and Canada. Invariably, upon inspection it turns out these valves are copies of Micro Matic valves in terms of basic design and functionality, but manufactured using inferior quality materials.
This particular failure often becomes evident first as kegs that will not drain properly during the purge cycles on keg cleaning lines and is caused by Internal delamination of the rubber CO2 valve. Delamination is the cracking, splitting and separation of the rubber from the metal spine embedded within the CO2 valve, most often a result of being manufactured with low-grade black rubber. Rarely, it will also occur in valves after 7-10 or more years of heavy use and possibly from excessively strong chemical solution or excessively hot steam sanitation on cleaning/filling lines.
Visual inspection of the valve in the keg shows no evidence of damage, since the problem is internal. The valve will often continue to perform for some time with this damage, allowing kegs to be filled with beer and beer to be dispensed. The problem on the keg line is caused by flaps of rubber torn loose from the valve, sealing the valve closed while in the open position due to reverse flow when cleaning solution must evacuate the keg on the side of the valve normally used for CO2 gas entering the keg for dispense.
Delamination also creates un-hygienic conditions – it’s impossible to fully clean and sanitize cracked, torn rubber parts – and eventually will result in a “leaker keg.”
If you are experiencing this type of valve failure, your best option is to replace the spear with a new one. Your keg supplier may be able to offer solutions.
I hope this info is helpful.
Source: Jon @BA Forum