Spirax-Sarco, which makes steam traps and pumps for industries such as food and beverage, healthcare, chemical and power generation, said the purchase consideration would be financed from new debt facilities supplied by its existing banks.
Shares in Spirax were up 5.6 percent at 5,605 pence at 0709 GMT, making the stock the second largest gainer on London's Midcap Index
The acquisition of Chromalox, which has five manufacturing facilities across North America, France and China, will add to Spirax's earnings in 2017, it said.
Liberum analysts, rating Spirax at "hold", wrote in a note that at first look, this deal would add to 2017 EPS by 13 percent, assuming no growth in the underlying business.
Chromalox earns about 18 percent of its sales from the oil and gas market where firms are cautious on spending as the industry recovers from a multi-year commodity price slump.
However, current order intake levels and market activity have shown improving prospects for Chromalox, Spirax said, adding its estimates sales of $190 million in the current year ending September.
Analysts at Jefferies, who have a "hold" rating on Spirax, said Chromalox looks to be a "highly complementary business" and a "very sensible/interesting deal".
The price tag of $415 million makes this Spirax's largest buy since the downturn of 2008. Last month Spirax said it would buy German firm Gestra AG, which makes valves and control systems for heat and fluid control, for 186 million euros (161.5 million pounds).
Chromalox will bring thermal energy management solutions to Spirax's customers, the British firm said, adding it would expand Spirax's total addressable market by 2.1 billion pounds to 7.9 billion pounds.
"We will invest in Chromalox to strengthen its direct sales channels globally; leverage our worldwide footprint to grow Chromalox's presence outside of its core markets in the USA," Spirax-Sarco said in a statement on Friday.
Completion of the deal is subject to a nod from the U.S. merger control authority, Spirax said, adding that the conditions are expected to be satisfied during its current quarter.
(Reporting by Noor Zainab Hussain in Bengaluru; Editing by Sunil Nair)
By Noor Zainab Hussain