PTSG employs around 1,200 people across 31 UK sites.
It operates through four divisions -Access & Safety, Electrical Services, Building Access Specialists and Fire Solutions servicing more than 180,000 buildings across the UK from its headquarters in Castleford, West Yorkshire.
Macquarie and PTSG confirmed on Friday that both sides had now reached agreement on the all cash offer.
PTSG made a pre-tax profit of £14.2m from a turnover of £69.1m for the year to December 31 2018.
Adam Joseph, Senior Managing Director,Macquarie Principal Finance Europe, said:”We view PTSG as a highly attractive leader in its chosens pecialist markets, with a strong track record of performance and reputationfor quality, value and safety.
“Health and safety is an increasingly key focus for businesses and PTSG’s experise means it will continue to play a critical role in providing safe working environments which comply with regulations and other requirements.
“We see a strong opportunity to partner with the management team in continuing to grow the business in core and adjacent markets, both organically and via strategic acquisitions, which is why we have made this compelling offer to shareholders at an attractive premium.”