Operating Segments (Details 2) (USD $)	3 Months Ended		9 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2013	Apr. 30, 2012
Information as to operating segments
Net sales	$ 105,009,000	$ 97,238,000	$ 311,053,000	$ 287,797,000
Operating Income:	14,223,000	13,774,000	47,058,000	37,715,000
General corporate expenses	(31,261,000)	(28,845,000)	(87,304,000)	(83,675,000)
Interest expense, net	(733,000)	(884,000)	(2,141,000)	(2,861,000)
Other expense				(605,000)
Income before income taxes	13,490,000	12,890,000	44,917,000	34,249,000
Operating Segments
Information as to operating segments
Operating Income:	17,177,000	16,543,000	56,294,000	45,804,000
Endoscopy
Information as to operating segments
Net sales	39,694,000	38,606,000	115,795,000	115,037,000
Operating Income:	7,241,000	7,847,000	24,386,000	22,081,000
Water Purification and Filtration
Information as to operating segments
Net sales	29,473,000	25,955,000	88,099,000	76,505,000
Operating Income:	2,846,000	2,818,000	10,243,000	8,380,000
Healthcare Disposables
Information as to operating segments
Net sales	22,674,000	19,336,000	66,968,000	56,668,000
Operating Income:	3,991,000	3,529,000	12,791,000	9,138,000
Dialysis
Information as to operating segments
Net sales	8,072,000	8,902,000	25,019,000	27,180,000
Operating Income:	1,990,000	2,217,000	6,478,000	6,578,000
All Other
Information as to operating segments
Net sales	5,096,000	4,439,000	15,172,000	12,407,000
Operating Income:	1,109,000	132,000	2,396,000	(373,000)
General corporate
Information as to operating segments
General corporate expenses	$ (2,954,000)	$ (2,769,000)	$ (9,236,000)	$ (8,089,000)