Inspections Insure Reliable Hydrant Performance
Hydrants are installed principally for fire department use. Unlike other parts of a water works system, such as pumps, filters, flow meters, recording devices and other equipment whose functioning is under more or less constant surveillance, hydrants receive little use. In fact, some hydrants may not be used for a fire for years at a time.
For this reason, some procedure must be followed to assure satisfactory hydrant performance when they are needed for a fire. Experience has shown that the most practical procedure for providing this when-needed availability is a regular hydrant inspection program.
The frequency of inspections may vary from community to community, and from area to area in any one community, depending on variable factors. Inspections twice a year, if properly conducted, have proven to be satisfactory in most cases. It is relatively unimportant whether the fire department or the water department assumes this responsibility. The main consideration is to see that this work is done regularly and properly.
The actual time of the year for inspections will depend on the climate. Where the year-round weather is mild, semiannual inspections can be made at any time. In areas subject to freezing weather, it is advisable to make one in the fall and another in the spring. This method efficiently checks hydrant conditions, and needed repairs can be made before cold weather sets in; the spring inspection will reveal any damage that has occurred as a result of freezing weather or other factors.
Check hydrant card
1. On approaching the hydrant, check the hydrant record card or other form for accuracy of its information. A notation of any changes (e.g. location, type, other data) should be made at the scene and later transferred to some permanent record. A visual external inspection should be made for possible damage, such as a cracked barrel, which may have resulted from the hydrant having been struck by a motor vehicle; unauthorized usage that has damaged the operating nut; or vandalism which results in missing caps or chains or foreign objects being placed in the barrel.
2. Conduct a pressure test. This is done by removing one of the hydrant caps and replacing it with a special cap provided with a Bourdon pressure gage. A high-pressure hydrant gage may be used for the same purpose provided a cap or a shut-off nozzle is placed over its open end. Check all caps for tightness and open the air cock, if one is provided with the gage, or else partially loosen one cap before fully opening the main valve.
After water is discharged, indicating that the air has been exhausted close bleeder cock or tighten loose cap and record the static pressure reading. Inspect the bonnet, packing, and caulking around the nozzle outlets for leaks. Observe the ground around the hydrant to detect any underground leaks in the hydrant or a defective drain valve which has not closed. The bleeder cock should then be opened or the outlet cap loosened, and the main valve closed.
3. Remove an outlet cap (or two caps, if more than a single outlet) and open the main valve to flush the hydrant and check its operation. The hydrant should be opened wide if this can be done without damage to streets and nearby property. Distributing the flow over more than one outlet nozzle reduces the possibility of damage by decreasing the discharge velocity and throw of the stream.
If the water is discolored by sediment, the hydrant should be flowed until the discharge is reasonably clear. In opening and closing the main valve, any unusual stiffness in operation should be noted and reported.
4. After closing, hydrant drainage should be checked by observing the water receding in the barrel. After it has dropped out of sight, drainage can be checked by placing the palm of the hand over the outlet to see if air is being sucked in as water recedes.
If there is any doubt as to whether or not all the water has drained, a small weight on a cord or a lightweight chain may be lowered into the barrel to sound out the presence of water.
5. Freezing in hydrants may be detected by: Attempting to turn the hydrant stem and encountering difficulty. The stem will not turn if frozen solidly. If only slightly bound by ice, a hydrant wrench should be placed on the operating nut and smartly tapped. This may release the stem. Blows should be moderate to avoid breaking the valve rod.
Lowering a weighted object on a string into the barrel. Such may strike ice or come up wet indicating the presence of water.
6. Steam is the most satisfactory medium for thawing a frozen hydrant. In an emergency, quicklime is placed in the barrel with hot water, but this must be followed by a thorough flushing. The use of calcium carbide, or gasoline or other flammable liquids is not recommended for thawing.
Denatured alcohol is commonly used for preventing frozen hydrants in much the same manner as it is used in automobile radiators. Although common salt (sodium chloride) has been used, it is not recommended. Calcium chloride is more suitable, because it creates a solution with a lower freezing point, and has little or no corrosive action on iron and brass.
7. Where hydrant drain valves are in ground water, they should be plugged. Care should be taken to see that these hydrants are pumped out immediately after each test or usage during freezing weather.
8. A female hose coupling should be screwed on each outlet to determine if a connection can be made. Chains should be free of excess paint and should be straightened to insure free movement of the hydrant cap. Gaskets in the caps should be examined and replaced if necessary. All cap and outlet threads should be swabbed with a mixture of lubricating oil and graphite, using a small brush. The caps should then be screwed on hand tight.
9. If the hydrant requires the oiling of certain parts, this should be done during each inspection.
In addition to their regularly scheduled inspections, hydrants should be thoroughly inspected after use at fires. To make sure that this is done, many communities have an established procedure whereby the water utility inspection crew must be notified each time a hydrant is used by the fire department.
Moreover, during freezing weather certain hydrants which are known to give trouble should be checked as often as weekly or even daily. The schedule for such inspections will have to be determined on the basis of local conditions and experience. These situations include hydrants with poor drainage or those in areas where rising ground water may fill the barrel and freeze. In such instances it is usually not necessary to make a full inspection; free movement of the main and drip valves is usually sufficient without actually discharging water from the hydrant.
A definite procedure should be established to make certain that all defects found on inspections are reported and corrected as quickly as possible. If the hydrant cannot be used for fire fighting purposes, an out-of-service disk or other device should be placed on it so that the hydrant will not be connected in the event of a fire.
In cities where both hydrant inspection work and maintenance work are done by either the water utility or the fire department, the same crews should handle inspections and repairs so that the defect can be corrected immediately.
When inspections are made by the fire department and repairs are handled by the water utility, a daily written report of hydrant defects should be sent to the utility, and the fire department should be notified when the repairs have been completed. For quicker action, where hydrants are out of service, a telephone call should precede the written reports of the fire department.
The results of hydrant inspections should be recorded on an individual card or sheet. Information should include the date of each inspection, pressure observed, defects noted, and repairs made. This card can also be used for recording additional data, such as make, type or model, date of installation, dates painted, size of the water main, whether hydrant is on a dead end main or a main not cross-connected, pressures normally maintained and any other information necessary for proper maintenance.