KEY FEATURES • Prevents reverse flow and reduces surges • Completely mechanical and has no dependency on the pilot system • Silent operation PRODUCT OVERVIEW The Internal Drop Check (IDC) ensures quick positive shut-off whenever normal forward flow stops, this action will prevent reverse flow while reducing surge events. The IDC assembly is a spring assisted, silent, mechanical check option for standard Singer main valves and comes in sizes ranging from 2 in / 50 mm -36 in / 900 mm. The IDC is a standard feature on the 106-PTC and 206-PTC series control valves and is available as on optional add-on for control valves larger than 2 in / 50 mm. ORDERING INSTRUCTIONS Refer to page 244 for the order form and ordering instructions. Note: • PTC valves include the IDC • this IDC may be included as standard with some products STANDARD MATERIAL Inner Valve: ASTM A536 Ductile Iron Inner Valve Sleeve: B-62 Bronze or AISI 316 Stainless Steel Stem: AISI 316 Stainless Steel O-Ring Seals: Buna-N Spring is optional on 106 series valves larger than 10 in / 250 mm and 206 series valves larger than 12 in / 300 mm. (On all other sizes, the spring is included.)

MODEL 106-IDC / 206-IDC INTERNAL DROP CHECK | 106-NYM / 206-NYM INTERNAL DROP CHECK NO YELLOW METAL PRODUCT LINE DRAWING 1. IDC - Internal Drop Check 2. IDC Stem 3. Spring (optional) in sizes 10 in / 250 mm and larger 106 4. Inner Valve 5. Disc Retainer 6. Inner Valve Sleeve Main valve fully open: Diaphragm and inner valve assembly controlled by the pilot system. Valve fully closed: Pressure above diaphragm drives diaphragm assembly and IDC down to seal the valve. 1 2 3 4 5 6 Should forward flow stop for any reason, the IDC moves down to seal against reverse flow, regardless of the valve position....