Analytical Scientific Instruments (Richmond, Calif., 510- 223-9670)
sells check valves for Perkin Elmer Series 4, 400, 410, 620, and 4000 for
$110 (inlet or outlet). I never heard of a PE 200.
This is a relatively new company to my knowledge. We recently
bought some HP 1090 check valves from them at a considerable savings
compared with HP. Have not had them long enough to give any opinion on
quality.
David
David A. Schooley
Dept. of Biochemistry/330
Univ. of Nevada
Reno, NV 89557
schooley@med.unr.edu
tel: (702) 784-4136; fax (702) 784-1419