A flexible seal for use in a solid oxide fuel cell stack is formed from a fibre matrix impregnated with a plurality of solid particles. In non-limiting representative example, the bulk chemical canister may have a capacity of 200 liters. A semiconductor wafer is subjected to an electrical test, so that it is possible to detect the aforementioned failures with good accuracy during a manufacturing process. When a valve is installed within the apparatus and the inlet is coupled to a source of high-pressure hydraulic fluid, the actuation pressure of the valve may be determined by monitoring the instrumentation. A mattress opening defined between lateral edges extends laterally through the sidewall portion. The cover member includes a cover-side identification part, and the housing includes a housing-side identification part which allows the cover member being paired with the housing to be appropriately attached to the housing, and which prevents the cover member not being paired with the housing from being appropriately attached to the housing, in cooperation with the cover-side identification part.