title: how many maximum session of a particular browser can be opened using selenium
body: <pre><code>i am trying doing automation using selenium......i have opened a hub by 
  `start java -jar selenium-server-standalone-2.40.0.jar -role hub -port 6156`
  and then started a node on a fifefox browser by 
  `start java -jar selenium-server-standalone-2.40.0.jar -role node -hub
  http://localhost:6156/grid/register -browser                                                                                                                                 "browserName=firefox,setjavascriptEnabled=true,acceptSslCerts=true,maxInstances=5,platform=WINDOWS" -port 6157`
  </code></pre>
  
  <p>here i mentioned maxInstances=5, if i change it to 10 then also at one instance only 5 browser is opening.......can anybody suggest that is it a restriction in selenium that at one instance we can have only maxium 5 instance of a particular browser opening......how many maxium session of firefox can i open at one time.</p>