Philadelphia, which owns the best record in the Eastern Conference, built a 4-0 lead in the second period and coasted to the finish. Ilya Bryzgalov stopped 31 shots, the lone flaw in his performance a tap-in by Jeff Halpern with 6:01 left.
The Flyers were without the NHL's leading scorer, Claude Giroux, who is out indefinitely with a concussion. The right wing accumulated 16 goals and 23 assists in Philadelphia's first 28 games, but in this one the Flyers generated more than enough offense without him.
Washington had its two-game winning streak snapped and fell to 3-4 under coach Dale Hunter. The Capitals' first three losses with Hunter behind the bench were each by one goal.
The Capitals were 7-0-3 in their previous 10 games against Philadelphia, including a 5-2 win on Oct. 20.
The Flyers killed two Washington power plays in the first period, limited the Capitals to only five shots and took a 1-0 lead at 16:16 when Hartnell took a wrist shot from the top of the left circle that slipped between the legs of goalie Tomas Vokoun.
Hartnell has six goals and two assists during the Flyers' six-game win streak.
Philadelphia went up 2-0 at 7:23 of the second period when Bourdon took a slap shot from just inside the blue line that ticked off the stick of Capitals defenseman Mathieu Perreault and whizzed past Vokoun, who was screened by Flyers defenseman Jody Shelley. The 22-year-old Bourdon was playing in his 10th NHL game, all this season.
Wayne Simmonds made it 3-0 at 14:19 by deflecting a shot by Andrej Meszaros past Vokoun, and Maxime Talbot scored at 17:33 with a shot that hit Vokoun in the chest and bounded into the net.
After giving up four goals on 21 shots, Vokoun was pulled after the second period and replaced by Michal Neuvirth.
Jakub Voracek put the Flyers ahead 5-0 by deflecting a shot by James van Riemsdyk at 5:26 of the final period.
NOTES: Philadelphia GM Paul Holmgren said the Flyers will be careful with Giroux. "Obviously, we're concerned. We're going to err on the side of caution," Holmgren said. ... Capitals D Mike Green missed a 15th straight game with a strained right groin muscle. He has missed 21 of the last 22 because of injuries. ... Philadelphia is 11-3-1 on the road, the best record in the Eastern Conference.