* Bernanke signals more easing to avoid deflation
* Dollar flips higher versus euro, currency basket
* US inflation slows, consumer sentiment dips
* OPEC says $75-$85 oil won't hurt global economy (Recasts, updates prices and market activity, changes by-line and dateline, previously LONDON)
By Gene Ramos
NEW YORK, Oct 15 (Reuters) - Oil fell sharply in thin, volatile trading on Friday, on course for its first weekly loss in four weeks as optoins expired and the dollar shifted higher, prompting profit-taking in oil futures ahead of the weekend.
Oil prices rose early in the session, after U.S. Federal Reserve Chairman Ben Bernanke signaled that the central bank would likely pump more money into the sagging economy.
At a speech in Boston, Bernanke said high unemployment and low inflation point to a need for a further easing of U.S. monetary policy, but offered no details on the central bank's next step. [
]That prompted investors to raise questions about the size and the timing of the widely expected purchases of government debt by the central bank in a second round of quantitative easing measures. The unease prompted profit-taking.
The expiry of options on Friday also pressured U.S. crude futures. Crude oil for November delivery <CLc1> fell $1.40, or 1.7 percent, to $81.29 a barrel by 1:00 p.m. EDT (1700 GMT). It hit a session low of $81.22.
ICE December Brent crude <LCOc1> dropped $1.64, or 1.9 percent to $82.56, after sliding to a low of $82.46.
The dollar weakened after Bernanke's statement but rallied later on the view that quantitative easing was already priced in. A stronger dollar makes commodities like oil more expensive for buyers holding other currencies.
"The oil slide started as the dollar continued to rise. But as November crude penetrates various strike prices, it causes traders to sell futures to protect against expiring option exposure," said Tom Bentz, broker at BNP Paribas Commodities Futures Inc in New York.
Economic reports kept pressure on the Federal Reserve to act soon to lessen the risk of a downward price spiral.
U.S. inflation unexpectedly slowed in September despite a pick-up in retail sales, the government said. A survey showed U.S. consumer sentiment unexpectedly dipped in early October to its weakest level since July, with buying plans declining,
On a brighter note, a gauge of manufacturing in New York State jumped in October, lifted by improvements in new orders.
"The market is still very jittery and everyone is trying to second guess the Fed," said Olivier Jakob, oil analyst at Petromatrix..."There is nothing really new in what he (Bernanke) said and the market was fully anticipating more quantitative easing already."
OPEC's secretary general said oil prices of $75-$85 a barrel would not hold back the global economy. Some members have called for higher prices to compensate for a weak U.S. dollar.
OPEC decided on Thursday to leave its oil output policy unchanged, as it has done since agreeing to a record output cut in December 2008. (Additional reporting by Robert Gibbons in New York and Joe Brock in New York; Editing by David Gregorio)