The Acquia Purge module allows Drupal sites hosted on Acquia Cloud to automatically purge (wipe) pages from their Varnish powered load balancers, as soon as content actually changed. The higher Drupal's "expiration of cached pages"-setting (TTL) is configured the more your site will be served directly off your load balancers. This effectively increases the efficiency of your site and lowers hardware costs, leaving more resources for back-end traffic. In most scenarios the module offers a full turn-key experience without requiring any technical configuration.
PHP Drupal API and application architecture design