Codeigniter v3 - Session User Agent

Hi,
I added user agent to session.
But dont cleaning flash data. What need i do ?

Here is my code:

PHP Code:

            $insert_data = array(
                'id'         => $session_id,
                'ip_address' => $_SERVER['REMOTE_ADDR'],
                'timestamp'  => time(),
                'user_agent' => substr($_SERVER['HTTP_USER_AGENT'], 0, 120),
                'data' => ($this->_platform === 'postgre' ? base64_encode($session_data) : $session_data)
            ); 


and this:

PHP Code:

if ($this->_config['match_useragent'])

 {
$this->_db->where('user_agent', substr($_SERVER['HTTP_USER_AGENT'], 0, 120));
} 


Thanks for helping.