actuator
alarm
alignment
arrow
bell
caution
colorful
conduit
connection
crisscross
emergency
equipment
extinguisher
faucet
fire
firefighting
fittings
flange
flow
hazard
hose
industry
instrument
intricate
joint
line
measurement
meter
parallel
pattern
pipe
pipeline
quake
red
resources
row
safety
sprinkler
stopcock
supply
system
tap
technology
tube
utility
valve
wall
warning
water