Generally the female fittings are on the outer ends of hoses to terminate air flow at the extreme end of the hoses and fittings. If you had the male fitting open end there, without a tool on it,and the compressor was running, it would not pressurize the system, just pump to atmosphere. An open male fitting at the end of the hose would also allow dirt in. The female quick disconnects don't. So - female quick connect on compressor or tank outlet female quick connect at tool end, male quick connect at compressor end on hoses male quick disconnect on tools. (this makes them easy to oil too. You do oil them I hope. 1drop air tool oil per 8 hr usage is recommended by most tool mfgr's) This is how I've seen it done most often, and have it done on my own system, with no issues. Best regards, Jeff Dayman ----- Original Message ----- From: "Harry Wade" <hww@xxxxxxxx> To: <modeleng@xxxxxxxxxxxxx> Sent: Wednesday, August 30, 2006 2:30 PM Subject: [modeleng] An Odd Question re (compressed) air lines > I need to rework my hodge-podge of compressed air hoses and > quick-connect fittings and wondered, is there a preferred direction for > fittings? For instance which direction should the male fitting point, > toward the air flow, or away from the air flow? > > > Regards, > Harry Wade > Nashville Tennessee > > MODEL ENGINEERING DISCUSSION LIST. > > To UNSUBSCRIBE from this list, send a blank email to, > modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line. > MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.