Dear All,
Just to bring some light into the development of nozzle check valves:
Mannesmann Demag developed the nozzle check valve with ring disk / radial guide design 1935!
For small sizes below 12 inch, the central piston nozzle check valve was designed by Mannesmann 1955.
Mokveld copied the piston type design for all sizes 1968 with some design changes.
Cameron is the legal succedor of the Mannesmann designs since Mannesmann was sold 1999.
Noreva is a split-off based on former Mannesmann staff, they have developed and intensively tested their valve performance at Delft Hydraulics institute (Last time 2007 - not 50 years ago)
The question is: Do you want a reliable, well established and tested valve with thousands of installations world-wide? Than you may look for Mokveld or Noreva.
Do you want a valve of nice R&D pictures with a questionable design (central piston combined with ring disk) that hasn't been independantly tested?
Than look somewhere else.
Schuck to me is not a real nozzle check valve as the guiding system is a simple guiding cross without a nozzle.