The company is spending a total of pounds 33m cash for PolyPhaser Corporation, a US company specialising in lightning protection for telecoms equipment, and Torin Holdings, a UK-based maker of ventilation and air movement products.
The two acquisitions bring the total spent since 1991 on the enlargement of the industrial division to pounds 273m. Since 1991, the division's annual sales have grown to pounds 328m and profits have grown to pounds 50m.
Keith Butler-Wheelhouse, chief executive of Smiths, said: "Greater focus on business areas where we can achieve market or technological leadership is the recipe for the industrial group's success.
"These two additions clearly enhance that process. They add more than pounds 20m to sales and broaden the range of markets we can serve. Both are expected to make a positive contribution to Smiths Industries' earnings in their first full year."
PolyPhaser is based near Reno, Nevada, and employs 140 people. It is one of the world's leading makers of lightning protection components and systems, principally for the wireless cellular telecoms industry.
Smiths has paid $28.7m (pounds 17.6m) for PolyPhaser and has acquired net assets valued at $7.2m. In 1996 the business made an operating profit of $4m.
Torin Holdings is being bought for pounds 15.5m. It sells its products primarily to original equipment manufacturers for use in computers, business machines, and heating/ventilation equipment for industrial and domestic applications. Its product range complements the activities of Smiths Industries' Vent- Axia division, which is the leading UK supplier of fans to the domestic, commercial and industrial markets, as well as fans for domestic central heating boilers.
Based at Swindon, Wiltshire, Torin employs 155 people, and is owned by the management, which is backed by institutional investors, with 3i the lead institutional shareholder.