High Flow Back Pressure Regulator; Sliding Gate; 1-1/2″ – 2″ (DN40 – DN50) Higher Steam Flow Without Upsizing – Cut Costs, Boost Efficiency, and Reduce Maintenance When your steam application demands higher flow capacity, but jumping to a larger line size isn’t in the budget-or the plant layout-you need a smarter solution. The Mark 501 and Mark 502 Series high flow back pressure regulators deliver high and ultra-high flow performance without the added cost, space, and complexity of upsizing. The Mark 501 handles flows up to Cv 50 (Kv 43), and the Mark 502 pushes that even further to Cv 70 (Kv 60)—giving you more throughput, more efficiency, and more control with the same line size. And thanks to precision-engineered sliding gate seats, these high flow back pressure regulators fight the internal build-up that often plagues high-flow steam systems. That means fewer shutdowns, less maintenance, and more uptime—so your operation keeps running hot, clean, and efficient.