Segment Information (Details) (USD $)	3 Months Ended										12 Months Ended
	Mar. 31, 2013		Dec. 30, 2012	Sep. 30, 2012	Jul. 01, 2012	Apr. 01, 2012		Jan. 01, 2012	Oct. 02, 2011	Jul. 03, 2011	Mar. 31, 2013		Apr. 01, 2012		Apr. 03, 2011
Summary of Segment Information
Sales	$ 87,601,000		$ 85,527,000	$ 87,160,000	$ 90,099,000	$ 83,210,000		$ 84,160,000	$ 87,870,000	$ 88,594,000	$ 350,387,000		$ 343,834,000		$ 297,641,000
Gross profit	14,307,000		8,126,000	19,196,000	15,307,000	13,512,000		15,679,000	18,750,000	17,927,000	56,936,000		65,868,000		61,902,000
Selling, general, and administrative expenses	8,307,000		7,617,000	7,455,000	8,227,000	7,895,000		7,163,000	7,844,000	7,857,000	31,606,000		30,759,000		29,940,000
Operating income	6,000,000		509,000	11,741,000	7,080,000	5,617,000		8,516,000	10,906,000	10,070,000	25,330,000		35,109,000		31,962,000
Identifiable assets	169,275,000	[1]				153,325,000	[1]				169,275,000	[1]	153,325,000	[1]	142,389,000	[1]
Unallocated Amount to Segment [Member]
Summary of Segment Information
Identifiable assets	52,900,000					48,000,000					52,900,000		48,000,000		41,700,000
Industrial [Member]
Summary of Segment Information
Sales											248,556,000		251,451,000		208,724,000
Gross profit											28,878,000		40,357,000		36,938,000
Selling, general, and administrative expenses											19,923,000		19,805,000		19,828,000
Operating income											8,955,000		20,552,000		17,110,000
Identifiable assets	143,827,000	[1]				129,782,000	[1]				143,827,000	[1]	129,782,000	[1]	121,250,000	[1]
Water Treatment [Member]
Summary of Segment Information
Sales											101,831,000		92,383,000		88,917,000
Gross profit											28,058,000		25,511,000		24,964,000
Selling, general, and administrative expenses											11,683,000		10,954,000		10,112,000
Operating income											16,375,000		14,557,000		14,852,000
Identifiable assets	25,448,000	[1]				23,543,000	[1]				25,448,000	[1]	23,543,000	[1]	21,139,000	[1]
Pharmaceutical [Member]
Summary of Segment Information
Assets associated with the discontinued operations	$ 0					$ 1,200,000					$ 0		$ 1,200,000		$ 900,000

[1] Unallocated assets consisting primarily of cash and cash equivalents, investments and prepaid expenses were $52.9 million at March 31, 2013, $48.0 million at April 1, 2012 and $41.7 million at April 3, 2011. Additionally, assets associated with the discontinued operations of the Pharmaceutical segment were zero at March 31, 2013, $1.2 million at April 1, 2012 and $0.9 million at April 3, 2011.