RFR HAZARD WARNING SIGNS

STACK GAS WARNING SIGN A warning sign to alert personnel working aloft near smoke pipe (stack) gases is shown in figure 3-7. One sign should be mounted near the bottom of each access ladder leading aloft. Another sign should be located at the top of each ladder but mounted on the base of the antenna pedestal. RFR HAZARD WARNING SIGNS There are six RFR radiation hazard (RADHAZ) warning signs (fig.3-8). Requisitioning information is provided on the signs themselves. Consult with your leading petty officer (LPO) to obtain the appropriate signs if they are not posted in your workspace. RADHAZ signs are made of anodized aluminum and come in two authorized sizes: large (14-inches by 14-inches) and small (5-inches by 5-inches). The large signs are reserved for shore use. The small signs may be used either aboard ship or ashore. The signs shown in figure 3-8 were approved for use in 1990. Some old style signs may still be posted in various work areas. If you find older style RADHAZ signs posted in an area, you do not have to replace them with the new style signs unless they are damaged or illegible. The purpose of each type of RADHAZ sign is explained below. Type 1—“WARNING RADIO FREQUENCY HAZARD . . . KEEP MOVING” The type 1 sign advises personnel not to linger in an area surrounding HF antennas where RFR permissible exposure limit (PEL) can be exceeded. There is no danger from exposure to HF radiation in these areas for short periods. However, no one should remain within the area (defined by a 4-inch red line/circle on the deck) longer than 3 minutes within a 6 minute period. When type 1 signs are required, install them at eye level, or where they can be seen easily, outside the PEL boundary. Type 2—“WARNING RADIO FREQUENCY HAZARD . . . BEYOND THIS POINT” The type 2 sign is used to keep personnel from proceeding past a designated point unless they comply with established RADHAZ avoidance procedures. These procedures are discussed in ship’s doctrine, such as the “MAN ALOFT BILL.” You will probably not find deck markings in these areas. Type 2 signs are installed at eye level at the bottom of vertical ladders or suspended at waist level between the handrails of inclined ladders. When type 2 signs are used as temporary barriers, such as when weapons direction radars are radiating, they are installed at waist level on a nonmetallic line. Type 3—“WARNING RADIO FREQUENCY HAZARD . . . BURN HAZARD” The type 3 sign advises personnel to use special handling procedures when they touch a designated metallic object, or simply to not touch it. This object is an RFR burn source when it is illuminated by energy from a nearby transmitting antenna. Although the hazard may exist only at certain frequencies or power levels, personnel should regard the object as a hazard unless the transmitter is secured. 3-12 Figure 3-6.—High voltage warning sign. PERSONNEL ARE CAUTIONED TO GUARD AGAINST POISONOUS EFFECTS OF SMOKE PIPE GASES WHILE SERVICING EQUIPMENT ALOFT. WHEN SERVICING EQUIPMENT IN THE WAY OF SMOKE PIPE GASES USE OXYGEN BREATHING APPARATUS AND A TELEPHONE CHEST OR THROAT MICROPHONE SET FOR COMMUNICATION WITH OTHERS IN WORKING PARTY. OBTAIN NECESSARY EQUIPMENT BEFORE GOING ALOFT. Figure 3-7.—Stack gas warning sign.