Do hydraulic snubbers have to be installed with their reservoir in any particular orientation?

No, hydraulic snubbers donot have to be installed in any specific orientation. They can be in anyposition because it is a pressurized reservoir. Note: Previous generationhydraulic snubbers did require a reservoir to be oriented vertically, but thenew style does not have that same limitation.

Hydraulic Snubbers (Fig. 511 AD) with Protective Boots Designed for a Hydro-sulfuric Acid Environment in a Geothermal Power Plant
Hydraulic Snubbers