The most recent bid was $85 a share, which SPX rebuffed on June 21, reports say. On May 27 SPX Flow had turned down an offer of $81.50 a share from IR.
Ingersoll's latest bid represents a 37% premium over SPX Flow's Friday closing price of $62.09.
Shares of SPX Flow, Charlotte, at last check jumped 29% to $80.39. Ingersoll Rand, Davidson, N.C., was unchanged at $48.16.
"[While] we believe that SPX Flow is a strong strategic fit with Ingersoll Rand, we will be disciplined in our approach and not stray from our demonstrated commitment to pursuing accretive transactions that present significant, additional post-synergy value creation opportunities," Ingersoll Rand Chief Executive Vicente Reynal said in a statement.
When SPX's board rejected the latest offer on June 21, it also declined Ingersoll Rand's request to negotiate a merger.
Ingersoll Rand said it had been willing to enter a "customary standstill and non-disclosure agreement." And it said a deal could be closed quickly and with no financing contingency.
Ingersoll Rand in 2020 merged with Gardner Denver.
The Wall Street Journal reported that that deal combined Gardner Denver’s compressor, pump, vacuum and blower products and services with Ingersoll Rand's similar businesses and IR's golf carts as well as equipment for lifting and material handling.
Ingersoll Rand’s heating, ventilation and air- and temperature-controlled transport businesses became Trane Technologies. TT
Last month, Ingersoll Rand sold its golf-cart business to the Los Angeles private-equity firm Platinum Equity for $1.68 billion.