For applications requiring no dead volume anywhere within the valve, which is commonly the case in instrument sampling, Conant provides both stack and selector valves in sizes listed above.

One model has welded-in tube stubs, which protrude from the body of the valve, so that compression fittings may be connected easily to the stubs. The other model has tube fittings welded to the body of the valve to simplify connecting metal or plastic tubing.
Both models eliminate the dead volume space between the valve rotor and the fitting.

Both the stack and selector valves can be fabricated in either Hastelloy® C-276 or Hastelloy® B-2.

Hastelloy® C-276 resists a broad range of corrosive chemicals. It is particularly well-suited for handling strong oxidizers, such as ferric and cupric chlorides, hot contaminated mineral acids, formic and acetic acids, acetic anhydride, sea water and brine solutions. Hastelloy® C-276 is one of the few materials that can withstand the corrosive effects of wet chlorine gas, sodium hypochlorite, and chlorine dioxide solutions.

Hastelloy® B-2 is recommended for applications involving all concentrations of hydrochloric acid at temperatures through their boiling points. This alloy resists a variety of other corrosive chemicals, like hydrogen chloride gas and sulfuric, acetic, and phosphoric acids.

Conant has developed a line of valves for control panel and instrument sampling applications which are certified to meet the standards put forth by the National Association of Corrosion Engineers (NACE) for equipment used in sour environments. The NACE Standard, MR-01-75 (Revised), covers metallic material requirements for resistance to "sulfide stress cracking for petroleum production, drilling, gathering and flowline equipment, and field processing facilities to be used in H2S bearing hydrocarbon service." The bodies and rotors of all these special selector valves, stack valves, and control vent valves are constructed of metals which resist sulfide stress cracking. Rotor sleeves on all valves are made of self-lubricating Teflon®.

Conant valves for use in sour environments are permanently marked to indicate their compliance with the NACE Standard.