Photographer's Page Introduction Controlling water temperature is critical for photographic processing. We make two series of valves that hold water temperature to +/- 0.2 degrees Fahrenheit, the D Series and the K Series. These valves are called water temperature control valves, mixing valves, tempering valves, thermostatic valves, etc. No matter what you call them, they are an important tool to aid in fine photographic processing. See our article A Biased Guide to Water Temperature Control in Photographic Darkrooms for more information. See below for a comparison between the D Series and the K Series. Product Description and Use Intellifaucet D Series Accurate, low-cost computer controlled water mixing valve. Used by serious amateur and professionial photographers in home darkrooms and professional photolabs. (Two Intellifaucet D250s are used with every Kodak K-Lab Kodachrome Processing machine!)  More info... Intellifaucet K Series Full-featured water mixing valve in sizes up to 42 gallons per minute. Used by professional photolabs, commercial labs, photographic film and paper manufacturers.  More info... Water Filters High quality water filter housings and replacement cartridges. Available for cold and hot water. Used in photographic darkrooms to filter incoming water to protect sensitive emulsions. Universal filter brackets and filter wrenches also available.  More info... Comparison between the D and K Series Feature D Series K Series Price $695 - $895 $1,095 - $3,895 Temperature Range 65F - 115F 40F - 140F Standard 34F - 180F Custom Temperature Selection  15 pre-selected temperatures chosen in consultation with numerous photolabs 0.1 degree F increment over full range Presets 15 1, Power-up preset, 100 deg F. Custom preset available, specify "Special - XX deg F power-up temperature" when ordering. Flow Control None - must use external hand valve 15 - 100 % Flow Range 250 Size: 1/4 - 5 GPM* 375 Size: 1 - 12 GPM 250 Size: 1/4 - 4.2 GPM 375 Size: 1 - 10 GPM 500 Size: 2 - 21 GPM 750 Size: 5 - 42 GPM Display Ready light on when actual temperature is in tolerance Digital display of actual temperature and temperature, flow and time settings. Brightness control None - must use electrical tape or equal to cover LEDs On/Off button on keypad Manual control Must remove caps and use screwdriver to operate valves Manual control knobs Timed shutoff None 1 minute to 4 hours *Flows down to 1/4 GPM are now standard for the Intellifaucet D250.