Once you establish drilling fluid returns, you must install and maintain the following drilling fluid-system monitoring equipment throughout subsequent drilling operations. This equipment must have the following indicators on the rig floor:
    
    
        
        (a) 
         Pit level indicator to determine drilling fluid-pit volume gains and losses. This indicator must include both a visual and an audible warning device;
     
    
        
        (b) 
         Volume measuring device to accurately determine drilling fluid volumes required to fill the hole on trips;
     
    
        
        (c) 
         Return indicator devices that indicate the relationship between drilling fluid-return flow rate and pump discharge rate. This indicator must include both a visual and an audible warning device; and
     
    
        
        (d) 
         Gas-detecting equipment to monitor the drilling fluid returns. The indicator may be located in the drilling fluid-logging compartment or on the rig floor. If the indicators are only in the logging compartment, you must continually man the equipment and  have a means of immediate communication with the rig floor. If the indicators are on the rig floor only, you must install an audible alarm.
     
    
        
            Code of Federal Regulations
        
        [68 FR 8423, Feb. 20, 2003]