If you only embed the Olark code on a single page, chats would end as soon as the visitor navigated away. Instead, use our API. Include the Olark embed code on every page as usual, but hide the chat box on every page except the one on which you'd like visitors to reach out to you, such as a contact page.
<script type='text/javascript> olark('api.box.hide'); olark('api.visitor.getDetails', function(details){ if (details.isConversing) { olark('api.box.show'); } }); </script>