Temperature Optimization Within 2 Uniquely Designed Courier Lockboxes During Extreme Summer Temperatures.

Abstract

To determine optimal temperature profiles for 2 uniquely designed courier lockboxes (steel vs polymer) by standardizing daily ice (-20ºC) and cold (4-8ºC) pack placement. Paired courier lockboxes were placed outside in direct sunlight. Ambient outdoor and lockbox temperatures were monitored during 2 4-day cycles, and temperature mean and range were determined daily (time frame, 4:00-10:00 pm). Control lockboxes without packs were compared with experimental paired lockboxes with either 2 cold packs placed at 4:00 pm or 4 ice packs placed at 8:00 am and replaced with 4 cold packs at 4:00 pm daily. Cycle 1 mean temperatures within control steel and polymer lockboxes were 31.8ºC (range, 18.4-44.1ºC) and 37.2ºC (range, 27.1-46.7ºC), respectively. The addition of 2 cold packs at 4:00 pm reduced mean temperatures to 29.1ºC (range, 19.1-37.2ºC) and 25.3ºC (range, 20.0-31.6ºC) in steel and polymer boxes, respectively. Cycle 2 mean temperatures within control steel and polymer lockboxes were 28.3ºC (range, 22.4-40.8ºC) and 31.6ºC (range, 23.8-41.0ºC), respectively. The addition of 4 ice packs at 8:00 am and replacement with 4 cold packs at 4:00 pm reduced mean temperatures to 24.3ºC (range, 17.4-27.9ºC) and 13.4ºC (range, 6.6-18.1ºC) in steel and polymer boxes, respectively. Standardizing instructions for ice and cold packs can decrease internal courier lockbox temperatures.