OUT INTO THE noonday sun, they come. A half-dozen men in an array of casual outfits gather more or less ready for an event that either ought to be in the Guinness Book of World Records or probed for consumer fraud.

Somewhere there may be a more rapid flag-raising. Conceivably, elsewhere banners are more swiftly lowered. But nowhere else is it recorded that flags go both up and down at one time with such unflappable speed.

There, on the roof of the nation's Capitol, the men from the bulding's labor pool will raise and lower an average of 200 American flags daily on the battered flagpoles over a passageway between the Senate and the House of Representatives.

The flags are taken out of their boxes. One corner (not two) is snapped to the rope. Four or five tugs. It touches the top. Immediately it is reeled down with a single fluid motion. The entire process takes five seconds on a slow day.

The flags are folded back into boxes for delivery to senators and representatives with a certification that the banner has "flown" over the U.S. Capitol. Those lawmakers then dispatch these Stars and Stripes to constituents.

To an extent, it is true, the term "flown" is guaranteed by Big Brother. To make sure the Capitol, often known as the Temple of Liberty, is no refuge for anarchy, closed-circuit television allows supervisors to monitor the raising.

The precise reason for this supervision is lost in history's murk. But some remember that House pages, who once were assigned to raising the flags, preferred to leave the colors in their boxes and practice the manly art of cigarette smoking instead.

After a relaxing session of inhale and exhale on the green copper roof, the pages would return to their masters with the amiable fiction that all of the flags had been raised and returned to the correct cartons pursuant to order.

In fact, employes are not much more reverential now. "I suppose 99 percent of the people think they are getting one of those," said one, pointing at a large flag fluttering from one regular Capitol pole. "This thing is a farce."

There has been, in any case, some congressional reluctance to convey the full nature of the flag-raising to recipients on the ground that the knowledge may be at least the equivalent of the heartbreak of psoriasis.

"It doesn't seem fair to tell them the flag only spent a second at the top of the pole," said an aide to one Minnesota congressman. "The people who get them think it is such a big deal."

The biggest deal in Capitol flag-raising occurred for obvious reasons on July 4, 1976. During that 24-hour Bicentennial period, 50 men working with precision at 20 poles hoisted 10,471 flags over the Capitol.

The whole thing began in 1937 when House members started requesting the Capitol's worn-out flags. With the growth of demand, the time the flags flew over the Capitol steadily diminished. About 62,800 were raised in record-breaking 1976. The number is expected to be about 50,000 in 1980.

Just how much the flag-raising costs the taxpayer is uncertain. The flag office in the Capitol has five employes who coordinate and certify. It's under the direction of the Capitol architect, whose office says $50,000 is budgeted for the exercise.

The taxpayer also pays for the men who raise and lower the flags, the cost of mailing and other overhead expenditures. The recipient of the flag, however, pays the congressman for the cost of purchasing the banner.

To get one, contact your congressman. For reasons relating to volume and time of purchase, the two chambers have different price lists. With the exception of its smallest cotton flag, the Senate's are more expensive.

But in either chamber it's a bargain. Thier flag prices are two-thirds less than the retail in Washington. Thus, Congress rejects the immortal Fourth of July admonition of the late Sen. Everett Dirksen, "Don't undersell Old Glory."