Abstract: A detonation flame arrester device including a left and right housing assembly containing two flapper plates positioned one in either side of the housing assembly and separated by a channeled barrier in the form of a stacked plate flame arrester designed to allow vapor passage under normal non-activated conditions. The flapper plates are positioned at an angle to be forced shut in advance of a detonation or deflagration wave coming from either direction and propagating through a piping system. The flapper plate is activated by the action of the pressure front on the flapper plate, and each plate is of a size and shape to cover the entire cross sectional area of the housing assembly. The flapper plates can optionally be slammed shut by torsion springs activated through alternate activation devices.

Abstract: A feeding tube assembly for nasogastric and nasointestinal enteral feeding with a pH indicator carried by a stiffener used for inserting the feeding tube into a patient. After insertion of the end of feeding tube assembly into the patient but before the stiffener is withdrawn from the tube, the pH indicator is in communication with body fluids which ooze into the lumen of the tube through perforations provided along the distal end thereof. Misplacement of the end of the tube in the patient's tracheobronchial tree is ruled out by noting that the pH indicator has changed color indicating that it has contacted stomach acid.