Segment Information (Details) (USD $)	3 Months Ended									12 Months Ended
	Mar. 30, 2014	Dec. 29, 2013	Sep. 29, 2013	Jun. 30, 2013	Mar. 31, 2013		Dec. 30, 2012	Sep. 30, 2012	Jul. 01, 2012	Mar. 30, 2014	Mar. 31, 2013		Apr. 01, 2012
Summary of Segment Information
Sales	$ 85,223,000	$ 81,697,000	$ 86,599,000	$ 94,744,000	$ 87,601,000		$ 85,527,000	$ 87,160,000	$ 90,099,000	$ 348,263,000	$ 350,387,000		$ 343,834,000
Gross profit	14,249,000	13,550,000	16,570,000	17,231,000	14,307,000		8,126,000	19,196,000	15,307,000	61,600,000	56,936,000		65,868,000
Selling, general, and administrative expenses	8,080,000	8,167,000	8,293,000	8,970,000	8,307,000		7,617,000	7,455,000	8,227,000	33,510,000	31,606,000		30,759,000
Operating income	6,169,000	5,383,000	8,277,000	8,261,000	6,000,000		509,000	11,741,000	7,080,000	28,090,000	25,330,000		35,109,000
Identifiable assets	170,507,000				169,275,000	[1]				170,507,000	169,275,000	[1]	153,325,000	[1]
Unallocated Amount to Segment [Member]
Summary of Segment Information
Identifiable assets	66,700,000				52,900,000					66,700,000	52,900,000		48,000,000
Industrial [Member]
Summary of Segment Information
Sales										244,888,000	248,556,000		251,451,000
Gross profit										32,041,000	28,878,000		40,357,000
Selling, general, and administrative expenses										19,781,000	19,923,000		19,805,000
Operating income										12,260,000	8,955,000		20,552,000
Identifiable assets	141,506,000				143,827,000	[1]				141,506,000	143,827,000	[1]	129,782,000	[1]
Water Treatment [Member]
Summary of Segment Information
Sales										103,375,000	101,831,000		92,383,000
Gross profit										29,559,000	28,058,000		25,511,000
Selling, general, and administrative expenses										13,729,000	11,683,000		10,954,000
Operating income										15,830,000	16,375,000		14,557,000
Identifiable assets	29,001,000				25,448,000	[1]				29,001,000	25,448,000	[1]	23,543,000	[1]
Pharmaceutical [Member]
Summary of Segment Information
Assets associated with the discontinued operations	$ 0									$ 0			$ 1,200,000

[1] Unallocated assets consisting primarily of cash and cash equivalents, investments and prepaid expenses were $66.7 million at March 30, 2014, $52.9 million at March 31, 2013 and $48.0 million at April 1, 2012. Additionally, assets associated with the discontinued operations of the Pharmaceutical segment were zero at March 30, 2014 and March 31, 2013, and $1.2 million at April 1, 2012.