Vitreous Sanitary Appliances (Vitreous China) -, Part 8: Specific Requirements of Pedestal Close Coupled Washdown and Symphonic Water Closets
2004 Edition

IS 2556 Part 8 details four primary design patterns for pedestal close-coupled water closets constructed from vitreous china: Pattern 1 features a double trap syphonic design with either 'S' or 'P' traps; Pattern 2 includes a single trap syphonic variant also utilizing 'S' or 'P' traps; Pattern 3 is a washdown type employing 'P', 'S', or concealed 'S' traps; and Pattern 4 is a washdown model with a horizontal outlet. Each pattern specifies important functional dimensions such as height, width, water seal depth, water surface area, bolt hole spacing, and opening sizes, which ensure proper fit and performance. Additionally, Pattern 4 requires the outlet to be grooveless and fully glazed externally, with all patterns demanding smooth, uniform glazing inside and low-level coupled flushing cisterns conforming to IS 774 or IS 7231.

The standard permits integral traps classified as 'S' traps, 'P' traps, concealed 'S' traps, and horizontal outlet types. 'S' and 'P' traps are illustrated in specified figures, with the concealed 'S' trap and horizontal outlet having distinct dimensional requirements. The internal outlet diameter must be at least 80 mm, with typical outlet angles of 104° for syphonic and washdown types and 90° for horizontal outlets. Heights of outlet centers, trap end distances, and grooved outlet lengths are specified to maintain plumbing compatibility. Surface glazing must be uniform and smooth, and seat bolt holes must be spaced between 160 and 175 mm.

Water closets must undergo several performance assessments to comply with IS 2556 Part 8. The flushing test involves filling the WC with colored water to the designated water seal level, activating the flush, and observing splash patterns; up to 10 isolated droplets on the floor are acceptable. The load bearing test requires applying a load of 400 ± 5 kg (approximately 4 ± 0.5 kN) via a 100 mm by 100 mm wooden beam across the WC's opening for one hour, ensuring no damage or defects result. Additional requirements include having at least two floor fixing holes of minimum 6.5 mm diameter, self-draining flushing rims with weep holes, and smooth, uniformly glazed internal surfaces.

Functional dimensions encompass all measurements apart from those related to plumbing connections and are crucial for proper operation. Typical values include a height of 390 ± 10 mm, width of 360 ± 10 mm, water seal depth not less than 50 mm, and precise seat bolt hole positioning. Connecting dimensions, critical for installation compatibility, specify minimum internal outlet diameters of 80 mm, external diameters of 102 ± 5 mm, outlet center heights of 180 ± 10 mm for P-traps, and grooved outlet lengths of at least 40 mm where applicable. Seat bolt holes must be spaced between 160 and 175 mm with diameters of 15 ± 2 mm. Tolerances not explicitly stated defer to IS 2556 Part 1, and ovality within diameter limits is permitted.

Flushing cisterns must be of the low-level coupled variety conforming to IS 774 or IS 7231 standards and match the water closet's design capacity. A resilient gasket must be installed at the back inlet to ensure a watertight connection. The cistern and its lid should be positioned entirely below an inclined plane passing through the seat fixing holes, with an inclination of at least 8° from vertical to enhance seat stability. The inlet and overflow may be situated at the bottom, eliminating the need for a separate flush pipe. The connected water closet must successfully pass flushing tests in the installed configuration. Internal surfaces should be uniformly glazed and smooth to facilitate efficient flushing action.