Looking For A Delayed Egress Concept But Without The Lock

The customer wants to have it that if you open a door without entering a PIN code, a siren goes off. 

Is this for entry or exit?

GE Deluxe Door Alarm - $15

"You can select instant or delayed alarms with the flip of an easy-access switch. In the 'away' mode, you have 45 seconds to exit your home after you arm the system. When you get back home, simply open the door and deactivate the alarm within 30 seconds by entering your custom four-digit code. The 30-second delay helps to eliminate false triggering of the alarm. When you're home, simply select 'Home' mode for an instant alarm. "

Brian's suggestion is a good one for an inexpensive solution. If you want something more commercial, you could look at the Alarm Lock PG30, which goes for around $250 online.

Back in ancient times when I was a tech, we would build something similar using a stand-alone keypad, magnetic contact switch, audible sounder, power supply and relay. These days, components alone would probably cost more than the solutions suggested above.

What you're looking for is a Door Prop/Forced door alarm. Several manufacturers offer them- SDC, Camden Door Controls perhaps, Alarm Controls (now part of Assa Abloy), look at STI also. I find that these prepackaged warning systems are very pricey for the functions that they do as you have stated. Could it be done using an intrusion alarm system? A wireless door sensor and wireless keypad at each door? Or perhaps a standalone keypad (would require local power at each door) that shunts a wired door contact that is connected to a wireless transmitter that is programmed into an intrusion panel that is programed to function in the way you want. Some intrusion keypads include an input/output built into the keypad that you could use to switch on a warning sounder/siren at the door (I.E. DSC)

We use to use a combination of Ritron UHF quick alerts with door contacts, a relay and timer and keypad to do Open Door notifications during school hours at Public Schools ...Basically during the day the doors were not to be used however the practice of chaining them closed during the day was frowned upon for obvious reasons < this was still being done however less then 10 years ago the doors had crash bars for egress but were secured for ingress

>...When the doors were open we had a local alarm and strobe go off as well as a radio notification that was sent to a Security Channel...We did this at pool entrances as well...the system could be shunted with an Alarm Keylock or keypad and we set up the times the doors were secured electronically via the programmable timer we installed...I still have them in operation however they were not cheap...Works very well...

Good luck 

Dennis