The pair came together with their side in desperate trouble at 58 for 6 after pace bowler David Thompson had marked his County Championship debut by taking the wickets of Russell Warren, Tony Penberthy and Graeme Swann in 16 balls.
The pair were still together at tea with Northamptonshire on 304 for 6 from 72 overs, having posted an unbroken 246 to alter the complexion of the match. Their stand surpassed the previous county best of 229, compiled by Wilf Timms and Fanny Walden against Warwickshire at Northampton in 1926.
Sales' undefeated 147 off 194 balls contained 26 fours, while acting captain Ripley had 73 to his name.
It was a far cry from the day's early exchanges which were entirely dominated by the Essex seam attack after Ripley chose to bat first. Ronnie Irani, leading the visitors in the absence of Nasser Hussain, sent back openers David Roberts and Alec Swann in his opening burst, and when Ashley Cowan had Mal Loye taken in the gully Northamptonshire were struggling at 12 for 3.
Thompson got into the act, claiming his first championship wicket when Warren obligingly clipped one straight to Stephen Peters at backward square-leg in the 23-year-old's second over.
He struck two further blows by trapping Penberthy and the younger Swann with deliveries of full length. But Essex found further success elusive as Sales - who hit 101 in Northamptonshire's previous championship match against Yorkshire at Scarborough last week - and Ripley dug in.
Sales dominated the scoring and enjoyed a stroke of luck on 93 when he edged Peter Such to slip only for Stuart Law to spill the chance. He completed his century off 139 balls, and Northamptonshire were also boosted by a tally of 62 extras, including 30 in no-balls.
In the other Championship match beginning yesterday, bottom-placed Glamorgan had another difficult day, against in-form Durham at Cardiff.
The northerners were assisted by 50 from Jon Lewis, while captain David Boon (40no) and Nick Speak (56no) kept up the good work to take their team to 190 for 3.
Stephen Fleming's New Zealand tourists were embroiled in a feast of wickets against Leicestershire at Grace Road.
They bowled out the hosts for 125, second-string medium-pacer Andrew Penn finishing with figures of 6 for 51. But the Kiwis were soon struggling with the bat themselves, and their reply stuttered to 75 for 5 at tea, with Daniel Vettori unbeaten on 37 and Scott Boswell resting with figures of 3 for 31.
Sri Lanka A were not so successful against Surrey at The Oval, toiling in the sun as the hosts moved to 200 for 5 after two sessions, despite three wickets for Russell Arnold.
Opener Ian Ward hit 50, while Ben Hollioake (57) and Gary Butcher (25) added 81 in an unbeaten sixth-wicket stand to keep the hosts' first innings on course for a decent total.Reuse content