Nominal internal diameter	Internal diameter	External diameter	L	a	Number of holes per piece			water inlet area	Safe crushing strength
					Z1	Z2	Total holes
	d1	d3	+/-2%				Z
DN
mm	mm	mm	mm	mm	nos.	nos.	nos.	mm2/m	kN/m
100	100+/-3	131+/-3	1000	10	5	16	80	6283	28
150	151+/-5	186+/-4	1500	10	5	16	80	4189	28
200	202+/-5	242+/-5	1500	10	5	16	80	4189	28
200	202+/-5	242+/-5	1750	10	5	19	95	4261	28
250	252+/-6	296+/-6	2000	10	5	22	110	4321	34
300	302+/-7	351+/-7	2000	10	5	22	110	4321	34
400	402+/-8	460+/-8	2000	10	5	22	110	4321	44
500	496+/-9	581+/-9	2000	10	5	22	110	4321	60
600	603+/-12	721+/-12	2000	10	5	22	110	4321	70
700	704+/-15	831+/-15	2000	10	5	22	110	4321	81
Note:   a = the diameter of hole       Z1 = no. of holes per piece (radial)      Z2 = no. of holes per piece (longitudinal)
8mm, 12mm & 13mm diameter holes available on request