font-awesome-animation/scss/pulse.scss

$faa-pulse-speed: 2s;
@keyframes pulse {
  0%, 100% {
    transform: scale(1.1);
  }
  50% {
    transform: scale(0.8);
  }
}
.faa-pulse.animated,
.faa-pulse.animated-hover:hover,
.faa-parent.animated-hover:hover > .faa-pulse {
  animation: pulse $faa-pulse-speed linear infinite;
}
.faa-pulse.animated.faa-fast,
.faa-pulse.animated-hover.faa-fast:hover,
.faa-parent.animated-hover:hover > .faa-pulse.faa-fast {
  animation: pulse ($faa-pulse-speed * $faa-speed-coeff-fast) linear infinite;
}
.faa-pulse.animated.faa-slow,
.faa-pulse.animated-hover.faa-slow:hover,
.faa-parent.animated-hover:hover > .faa-pulse.faa-slow {
  animation: pulse ($faa-pulse-speed * $faa-speed-coeff-slow) linear infinite;
}